I don't believe poets need to have a prophetic message - but they should have a poetics, a reason to want to work with language, and, especially, love. Love is often ignored in aesthetics, but a poet who does not love poetry (or poems), is unlikely to create work of lasting interest, even beauty. Now, there may be some measure of antagonism, too ("wrestling with the materials" and so on) - but I feel someone approaching poetry, to learn its "trade", needs to be at least interested in reading poetry by other poets. But, further, should be willing to enter a lifetime engagement with the canon(s), the writing, the editing, the work, involved. Teachers can guide their students to this appreciation of the depths of poetry, while also reminding them of more practical aspects of the genre. There is something in contemporary society that doesn't love a poem, though. I call this The Celebrity Chef Problem. Everyone who has a skill aspires to promote it on TV, these days, in the UK.
Poets should resist this urge. Poetry can reach a wider audience, but on its own terms. Chefs can easily present their recipes to a public, but cooking (foodies, forgive me) is not enough to feed the soul. Poetry can be a way of life - but not in a "take it or leave it" consumerist society that thinks one can treat the art of poetry as one can pottery, or gardening - admirable activities, suited for being a hobby, but not, finally, fully directed at testing the limits of experience, and of wisdom.
This sounds elitist, but isn't - the best way to excite interest in poetry among all kinds of people is to let them realise not how "difficult" it is ("difficult" fails to encompass how profound the act of poetry is, can be) - but how engaged it is. There's a fear of "religion", of "commitment", of "fanaticism" in today's society - a fear fostered by a commodity-based society that wishes brand loyalties to be fluid, and flexible ("new and improved") - well, unfortunately, poetry is, like some kinds of philosophy, some kinds of religion, a total immersion in something other than the self: it is a commitment to reading serious, good poetry from all times, in all languages (tradition), and to pushing the limits of one's own verbal expressiveness. Poetry is not a half-pregnant art. Poetry is life, as big as life. If one wishes to be a gladiator, strap on the armour, and face the lions.