The basic premise of Jeremy Bentham's treatise is that mankind needs to be rewarded, or have some sort of incentive, to accomplish anything, and that, as just punishment is commensurate with the offense, a reward ought to be commensurate with the virtue done. (There is also a Rationale of Punishment, but that is not pertinent here). What is virtue, though? "Virtue is sometimes considered as an act, sometimes as a disposition: when it is exhibited by a positive act, it confers a service; when it is considered as a disposition, it is a chance of services. Apart from this notion of service, it is impossible to tell wherein virtue consists. To form clear ideas concerning it, it must altogether be referred to the notion of utility: utility is its object, as well as its motive . . . it is fostered by, and perhaps depends upon, esteem; but this is a secret which it seeks to hide from itself" (125-6). He establishes one first premise: all of every person's actions are limited to the object of utility. In this lies embedded the presumption that forms his famous attack on poetry*: namely, that all our actions, desires, motives, and interests are limited to concrete, human, material ends. Our intellects are purely in the interest of tangible goods, and the reward should be immediately satisfying. In these terms, he presents his argument on poetry: it is too difficult and too dangerous to be truly useful.Perhaps one of Bentham's best known ideas is that of poetry being equal, perhaps even lesser, than the game of push-pin, for the simple reason that push-pin, requiring little intellect and no discipline, affords a more immediately available form of pleasure to a greater number of people than poetry. The outrageous ideas in this are multitudinous. First, he supposes that all pleasures are equal; then, that there is no merit or obligation to develop the so-called higher faculties because the pleasure of poetry is incommensurate with the pains it requires to appreciate it. For, if all our actions lead only to material aims, then man is not truly an intellectual being; that is, he is not a contemplative being. And herein lies the greatest outrage of all, for to deny the contemplative nature of man is to deny not only his nature, but the nature of the Creator, as well.
There is more on this. John Stewart Mill introduces the idea of refinement of pleasure, but with the exception of a few deliberately ignored thinkers, the utilitarian premises of art have been accepted whole-scale even now, and we are content, even eager, to promote the idea that art is, by and large, useless.