Jay Parini touches all the bases in this argument for why poetry matters. It doesn't matter that he does, though. Poetry still doesn't matter. Like much else, it was killed by the 20th century.
In the 20th century, something went amiss. Poetry became "difficult." That is, poets began to reflect the complexities of modern culture, its fierce disjunctions. The poems of Ezra Pound, Hilda Doolittle, T.S. Eliot, Marianne Moore, and Wallace Stevens asked a lot of the reader, including a range of cultural references to topics that even in the early 1900s had become little known. To read Pound and Eliot with ease, for instance, one needed some knowledge of Greek and Latin poetry. That kind of learning had been fairly common among educated readers in the past, when the classics were the bedrock of any upper-middle-class education. The same could not be said for most readers in the 20th century — or today, when education has become more democratized and the study of the classics has been relegated to a small number of enthusiasts. The poems of the canonical poets of high modernism require heavy footnotes.
I'm inclined to take Hugh Kenner's observation that Pound and Eliot (the rest were following or reacting), after World War I, wrote poetry for an age in which poetry already was dead. Living in Europe, to them, Western civilization lay crushed (and how much of it did we ever get back?), the ancient libraries shelled and gutted, a generation of readers, critics, and writers gassed and rotting in the trenches. They wrote for the past, or directly for the anthologies, complete with numbered lines and footnotes, in hopes a future generation would arise and find the poems like time capsules.
Poets since have never gone back to that point and tried to recover the trail.
Meanwhile, for the few for whom it still matters, here Adam Kirsch reviews Stanley Plumly's new “Posthumous Keats”:
Yet the consolations of poetry, as “Posthumous Keats” reminds us, last only as long as the poem lasts. The sublimity of the odes did not stop Keats from suffering in body and mind, or from cursing the fate that allowed him to taste the pleasures of life and art so intensely, only to snatch them away. “Keats, of all poets, cannot be divided between the artist and the man,” Plumly writes. But in a sense it is precisely the violent sundering of the artist and the man that is Keats’s tragedy. The poet saw autumn as fulfillment, the season that “set budding more, / And still more, later flowers for the bees, / Until they think warm days will never cease.” The man died in winter, in a foreign country, certain that his work had not kept the promises his imagination made. “Is there another Life? Shall I awake and find all this a dream?” he asked in one of his last letters home. “There must be,” he decided. “We cannot be created for this sort of suffering.”