What is wrong with “expedient”? Briefly, it is deeply rooted in an ethical frame of reference which is about as diametrically opposed to the ethical perspective of the Lotus Sutra as one can get. The Random House Unabridged Dictionary has as its second definition of “expedient. conducive to advantage or interest, as opposed to right.” Moreover, “expediency” is defined as “a regard for what is polite or advantageous rather than what is right or just; a sense of self-interest.” Though one could argue that this term does not have to carry such freight, the fact of the matter is that it is deeply embedded in a biblical ethics which is essentially deontological because it is rooted in notions of divine commandment and human obedience. In John 11:49-50, for example, we find:

And one of them, named Caiaphas, being the high priest that year, said to them, “You know nothing at all. Nor do you consider that it is expedient for us, that one man should die for the people, and not that the whole nation perish.

And in several places, in the King James version at least, Saint Paul uses the term “expedient” to mean “profitable” to oneself. The Bible, of course, had a major impact on what terms mean in English.

Thus, a very basic meaning of “expedient” is an act which is done in spite of principle in order to benefit oneself. It is rooted in an ethics and in a vision of reality in which there is a radical, unbridgeable gap between principles and self-interest. Though they may be internalized, principles are given, by God or Nature, or the metaphysical structure of reality. Principles are lawlike, and thus their disobedience requires just punishment. To do the expedient thing is to ignore or go against what is right in order to gain some selfish benefit.

But this is exactly what, according to the Lotus Sutra, hōben cannot be. It is part of the very definition of hōben in the Lotus Sutra that it is always for the benefit of someone else. Not in this sutra, or in any other that I know of, is there even a single example of hōben in which the doer forsakes some principle for his or her own benefit.
A Buddhist Kaleidoscope; Gene Reeves, Appropriate Means as the Ethics of the Lotus Sutra, Page 380

The maximum commitment to serving others, united to awareness of the limits of every action, represents the dynamic realization of the Middle Path. Each limited and concrete action can certainly redeem just a fragment of the world, but through the prayer/meditation also a fragment becomes totality (ichinen sanzen). In this way, liberation is not put off to a utopian future, and suffering is not related to an inevitable karma or to the logic of economics or power. To the eyes of the Buddha and in the hand and heart of the Sangha, we are bound together by warm links of solidarity and loving kindness.

In other words, Buddhist liberation consists of the union of suffering and salvation. Redemption is not obtained through a sacrifice offered to a divinity which, with its intervention, “mends” the world, destroying what we qualify as negative and as a source of suffering. Redemption is found in overcoming conflict and opposition, and in the creation of a more subtle harmony between order and disorder. This is a path that doesn’t involve nonsuffering, but the nonsuffering-of-suffering; a path which, we could say according to French writer Marguerite Yourcenar, if it doesn’t make us mad with joy, at least it makes us wise with pain.

That is why we can affirm that this world, full of misery and conflict, is, nonetheless, the tranquil realm of the Buddha.
A Buddhist Kaleidoscope; Riccardo Venturini, A Buddha Teaches Only Bodhisattvas, Page 336

Taking others’ suffering on oneself and purifying it without allowing oneself to be contaminated is the mission of the bodhisattva, who clears a world polluted by ignorance and selfishness. As Saichō, the founder of Japan’s Tendai sect, said, “To take evil upon oneself and to give good to others, and to forget about oneself and to work for the benefit of all, is the ultimate in compassion.”

Not discriminating between friends and enemies, tending not to have “personal” needs, appreciating all beings and all situations, bodhisattvas never pause in their constant, merciful practice (nondualism in action), always treat others as they would like to be treated, and are always ready to help others to overcome their misery.
A Buddhist Kaleidoscope; Riccardo Venturini, A Buddha Teaches Only Bodhisattvas, Page 335

The Buddha in his wisdom can affirm that the world is already saved and pure. As the Lotus Sutra says, “Tranquil is this realm of mine.”
Nonetheless, in his compassion, since the world is full of beings who groan amid miseries of every kind, the logic of love draws him to reveal the Dharma to people devoid of wisdom and full of attachments:

The Triple World is not safe,
Just as the burning house,
Full of all kinds of sufferings,
Was greatly to be feared.
Ever there are the distresses of birth,
Old age, disease, and death;
…
Now this triple world
All is my domain;
The living beings in it
All are my sons.

But now this place
Abounds with distresses;
And I alone
Am able to save and protect them.

For this reason the buddhas appear in the world:

Because the buddhas, the world-honored ones, desire to cause all living beings to open [their eyes] to the Buddha-knowledge so that they may gain the pure [mind], [therefore] they appear in the world; because they desire to show all living beings the Buddha-knowledge, they appear in the world; because they desire to cause all living beings to apprehend the Buddha-knowledge, they appear in the world; because they desire to cause all living beings to enter the way of the Buddha-knowledge, they appear in the world.

For this reason Śākyamuni, the Eternal Buddha, says he is committed, for a time without end, to bodhisattva practice.
A Buddhist Kaleidoscope; Riccardo Venturini, A Buddha Teaches Only Bodhisattvas, Page 334-335

In the Lotus Sutra the Buddha affirms that he employed nirvana (in its meaning of extinction, cessation, emptiness in a negative sense) as a didactic method to save people blinded by ignorance and dominated by the thirst for existence:

For this reason …
I set up a tactful way for them,
Proclaiming the Way to end sufferings,
Revealing it through nirvana.
Though I proclaim nirvana,
Yet it is not real extinction.
All existence, from the beginning,
Is ever of the nirvana nature.”

It is important for Westerners, who have had a distorted and negative view of the Buddhist concepts of void and nirvana, to reflect on these words. Void, in fact, being emptied itself, becomes fullness. This changing and impermanent world in which we live is itself the real world. Any difference between nirvana and samsara vanishes; and the same nirvana, which as a “designation” is also empty and unreal, becomes alive and concrete in the realization of life’s indivisibility, in the collapse of self-centeredness and in the awareness of the interrelatedness of all things.

Bodhisattvas, then, do not live as ascetics in the desert of their spiritual pride, insensitive to the sufferings of unenlightened beings. The plight of those who suffer misery and delusion stirs their hearts and spurs them to compassionate acts, to which they subordinate their quest for their own enlightenment, having already chosen lives of absolute nondualism. Far from enjoying a separate happiness, bodhisattvas feel a “vicarious suffering,” with others and in the place of others. They do not therefore “renounce” nirvana but emancipate themselves from the pursuit of a false aim, living the true nirvana in a “return” to the everyday world.
A Buddhist Kaleidoscope; Riccardo Venturini, A Buddha Teaches Only Bodhisattvas, Page 333-334

When, through the mysterious concurrence of external and internal causes, the individual directs all his energies toward the Buddha, and the Buddha turns to that person, there occurs the awakening of the mind that aspires to enlightenment (bodhicitta) and to follow the Way of the Buddha and the path of spiritual discipline (bodhicitta-utpāda). It is the moment of “conversion” or great resolution, in which the bodhisattva, sustained by faith in enlightenment, takes great vows and is ready to set out on the path, to begin the journey of pāramitā practice.
A Buddhist Kaleidoscope; Riccardo Venturini, A Buddha Teaches Only Bodhisattvas, Page 333

Nichiren’s Tendai contemporaries … held the Lotus Sutra to be all inclusive, but generally took this to mean that, properly understood, any practice, such as chanting Amida Buddha’s name or invoking the Bodhisattva Kannon, could be considered practice of the Lotus Sutra. Nichiren decried this interpretation as a confusion of the true and the provisional and rejected all other, “pre-Lotus Sutra” teachings as no longer suited to the present time of mappō. Like medicine that stands too long on the shelf and becomes poisonous, these other teachings and the practices based upon them were, in his view, not only soteriologically useless but positively harmful. For Nichiren, to willfully set aside or ignore the Lotus in favor of other, “lesser” teachings amounted to “slander of the Dharma” and would pull the practitioner down into the lower realms of rebirth.

He therefore taught his followers that one should not only embrace faith in the Lotus Sutra oneself, but spread that faith to others, assertively rebuking adherence to other, provisional teachings. This is known as shakubuku, the “harsh method” of propagating the Dharma by actively challenging “wrong views.” Nichiren saw shakubuku as compassionate action that would enable others to form a connection with the Lotus Sutra and save them from both misfortune in this world and rebirth in the evil realms.
A Buddhist Kaleidoscope; Jacqueline I. Stone, When Disobedience Is Filial and Resistance is Loyal: The Lotus Sutra and Social Obligations in the Medieval Nichiren Tradition, Page 264

For Nichiren, the inherence of the pure land in the present world was not merely a matter of philosophical or contemplative insight; when individuals realized enlightenment, he taught, their world would be materially transformed:

When all people throughout the land enter the one Buddha vehicle and the Wonderful Dharma [of the Lotus] alone flourishes, because the people all chant Namu Myōhō Renge-kyō as one, the wind will not thrash the branches nor the rain fall hard enough to break clods. The age will become like the reigns of [the Chinese sage kings] Yao and Shun. In the present life, inauspicious calamities will be banished, and people will obtain the art of longevity. When the principle becomes manifest that both persons and dharmas “neither age nor die,” then each of you, behold! There can be no doubt of the sutra’s promise of “peace and security in the present world.”

This passage points to both continuities and breaks between Nichiren’s teaching and broader, contemporaneous currents of Buddhist thought. Teachings about the nonduality of this world and the Buddha’s pure land, expressed in such terminology as “the sahā world is the land of ever-tranquil light (shaba soku jakkōdo)” or “worldly truth embodies ultimate reality (zokutai nishin),” formed a standard doctrinal feature of both Tendai and Shingon esoteric Buddhist traditions. Similarly, belief in the apotropaic powers of the Buddha-Dharma to ensure harmony with nature and prosperity in the social sphere also was a common assumption underlying the sponsorship of esoteric rites for nation protection (chingo kokka). Nichiren’s distinctive reading of these ideas derived from his “single-practice” stance: The ideal Buddha-land could be realized in this world, but only by exclusive faith in the Lotus Sutra.
A Buddhist Kaleidoscope; Jacqueline I. Stone, When Disobedience Is Filial and Resistance is Loyal: The Lotus Sutra and Social Obligations in the Medieval Nichiren Tradition, Page 263

In the influential Tendai Buddhist tradition from which Nichiren emerged, the moral unity of the individual and the world was schematized in terms of the “nonduality of dependent and primary [karmic] recompense” (eshō funi). In other words, the individual’s karma or actions – thoughts, words, and deeds – were thought to bear cumulative fruit in two simultaneous and interconnected modes: as the collection of physical and mental aggregates that form individual living beings, and as those individuals’ outer circumstances or container world. Thus the living subject and his or her objective world were held to be fundamentally inseparable – a relationship that Nichiren likened to that of a body and its shadow. Moreover, because all phenomena are from a Mahayana standpoint without independent substance, the ten realms of existence from hell to Buddhahood were said to interpenetrate, each of the ten realms encompassing the others within itself. Thus for one who achieves awakening, the present world is the Buddha’s pure land.
A Buddhist Kaleidoscope; Jacqueline I. Stone, When Disobedience Is Filial and Resistance is Loyal: The Lotus Sutra and Social Obligations in the Medieval Nichiren Tradition, Page 262-263

Chih-i affirms that the phenomenal entities do provisionally (dependently) exist; simultaneously empty and dependently arising, their interpenetrating existence is a positive phenomenon, a reality that while not independent of conceptual activity is not merely the groundless correlate of conceptual acts. Chih-i’s affirmation of phenomenal existence is intimated by the Lotus Sutra’s elaborate descriptions of the wonder of the Buddha realm. This realm of the Buddha, filled with gardens of jewel trees, magnificent towers and halls, incense and music, is not a pure land beyond this world but the realm of phenomenal existence itself seen in its truth. In contrast to the Prajn͂āpāramitā sūtras, which emphasize the illusory nature of the phenomenal realm, the Lotus Sutra celebrates its “true aspect” with a profusion of concrete images.
A Buddhist Kaleidoscope; Susan Mattis, Chih-i and the Subtle Dharma of the Lotus Sutra: Emptiness or Buddha-nature?, Page 256