We might, no doubt,

find it a nuisance to count all the blades of grass or all the leaves of the trees; but this would not be because of our boldness or gaiety, but because of our lack of boldness and gaiety. The bore would go onward, bold and gay, and find the blades of grass as splendid as the swords of an army. The bore is stronger and more joyous than we are; he is a demi-god-nay, he is a god. For it is the gods who do not tire of the iteration of things; to them the nightfall is always new, and the last rose as red as the first.

G.K. Chesterton, “On Mr. Rudyard Kipling and Making the World Small“

All the towering materialism which dominates the modern mind rests ultimately upon one assumption; a false assumption. It is supposed that if a thing goes on repeating itself it is probably dead; a piece of clockwork. People feel that if the universe was personal it would vary; if the sun were alive it would dance. This is a fallacy even in relation to known fact. For the variation in human affairs is generally brought into them, not by life, but by death; by the dying down or breaking off of their strength or desire. A man varies his movements because of some slight element of failure or fatigue. He gets into an omnibus because he is tired of walking; or he walks because he is tired of sitting still. But if his life and joy were so gigantic that he never tired of going to Islington, he might go to Islington as regularly as the Thames goes to Sheerness. The very speed and ecstacy of his life would have the stillness of death. The sun rises every morning. I do not rise every morning; but the variation is due not to my activity, but to my inaction. Now, to put the matter in a popular phrase, it might be true that the sun rises regularly because he never gets tired of rising. His routine might be due, not to a lifelessness, but to a rush of life. The thing I mean can be seen, for instance, in children, when they find some game or joke that they specially enjoy. A child kicks his legs rhythmically through excess, not absence, of life. Because children have abounding vitality, because they are in spirit fierce and free, therefore they want things repeated and unchanged. They always say, “Do it again”; and the grown-up person does it again until he is nearly dead. For grown-up people are not strong enough to exult in monotony. But perhaps God is strong enough to exult in monotony. It is possible that God says every morning, “Do it again” to the sun; and every evening, “Do it again” to the moon. It may not be automatic necessity that makes all daisies alike; it may be that God makes every daisy separately, but has never got tired of making them. It may be that He has the eternal appetite of infancy; for we have sinned and grown old, and our Father is younger than we. The repetition in Nature may not be a mere recurrence; it may be a theatrical ENCORE. Heaven may ENCORE the bird who laid an egg. If the human being conceives and brings forth a human child instead of bringing forth a fish, or a bat, or a griffin, the reason may not be that we are fixed in an animal fate without life or purpose. It may be that our little tragedy has touched the gods, that they admire it from their starry galleries, and that at the end of every human drama man is called again and again before the curtain. Repetition may go on for millions of years, by mere choice, and at any instant it may stop. Man may stand on the earth generation after generation, and yet each birth be his positively last appearance.

G.K. Chesterton, “The Ethics of Elfland”

Art is useless because its aim is simply to create a mood.

Frank Stella, Gobba, zoppa e collorto (1985)

It is not meant to instruct, or to influence action in any way. It is superbly sterile, and the note of its pleasure is sterility. If the contemplation of a work of art is followed by activity of any kind, the work is either of a very second-rate order, or the spectator has failed to realise the complete artistic impression.

A work of art is useless as a flower is useless. A flower blossoms for its own joy. We gain a moment of joy by looking at it. That is all that is to be said about our relations to flowers. Of course man may sell the flower, and so make it useful to him, but this has nothing to do with the flower. It is not part of its essence. It is accidental. It is a misuse. All this is I fear very obscure. But the subject is a long one.

Oscar Wilde, Letter to Bernulf Clegg

What hides under this aestheticized "uselessness" of art?

Well, for one thing, a rationalization and universalization of Wilde's homosexuality. But that is a relatively trivial thing. 

In the late 19th century, aestheticism and "art for art's sake" become a means to defend art against its crude bourgeois instrumentalization. But this defense is already a compromise. From service to the sacred, which the modern world no longer appreciates or recognizes, art retreats into "uselessness," a refusal to serve the grosser requirements of bourgeois valuation. Because the sacred has been dispossessed of value, its vestigial presence in art can only be (weakly) upheld by a fetishization of art's uselessness, i.e. its material uselessness.

Clive Bell's theory of significant form shows more insight than Wilde's. Bell recognizes that form has metaphysical significance:

Significant form stands charged with the power to provoke aesthetic emotion in anyone capable of feeling it. The ideas of men go buzz and die like gnats; men change their institutions and their customs as they change their coats; the intellectual triumphs of one age are the follies of another; only great art remains stable and unobscure. Great art remains stable and unobscure because the feelings that it awakens are independent of time and place, because its kingdom is not of this world. [my emphasis] To those who have and hold a sense of the significance of form what does it matter whether the forms that move them were created in Paris the day before yesterday or in Babylon fifty centuries ago? The forms of art are inexhaustible; but all lead by the same road of aesthetic emotion to the same world of aesthetic ecstasy. 

There, in Bell's words, we have some indication that in its infancy, formalism was not the sterile thing it became after Clement Greenberg got a hold of it. Greenberg  "justified" formalism by reformulating it as a technocratic procedure for "entrenching" each art medium in its "area of competency." Making formal autocritique the focus of art practice was supposed to safeguard art from assimilation into kitsch. In actuality, this microscopic narrowing of focus ensured the complete desacralization of abstraction and, inevitably, its banalization.  This is evident in the utter vacuity of Frank Stella's postminimalist output, the precursor of most contemporary abstraction.

Nothing hastened the transformation of abstraction itself into kitsch than Greenberg's effort to remove from abstraction any reference to or suggestion of supra-formal content.