I really enjoyed reading Dana Gioia's 1992 essay Can Poetry Matter? (Link leads to free version available online.) This bit in particular about the importance of poetry really struck home to me:

Poetry is the art of using words charged with their utmost meaning. A society whose intellectual leaders lose the skill to shape, appreciate, and understand the power of language will become the slaves of those who retain it—be they politicians, preachers, copywriters, or newscasters. [emphasis added]