It's significant that ugly-truth-tellers are much more common in our fiction than our poetry. Much of our mainstream poetry is constrained by an ethic of sincerity and the unstated wish to be admired (if not admired, liked; if not liked, sympathized with). American poetry still largely believes, as romantics have for a few hundred years, that a poem is straightforward autobiographical testimony to, among other things, the decency of the speaker. And, for all the freedom and "opening up" engendered by Confessionalism, to be uninhibitedly mean, we all know, is itself prohibited. Welcome to Poetry City: hurt someone's feelings--go to jail.
The problem with such civility is that it excludes all kinds of subject matter that cannot be handled without contamination of the handler. American poetry of the last few decades has specialized in empathy, and many extraordinary poems have been written in that spirit--but all that warmth has banished the cold eye of the prosecutor. To some extent, the decay of fierce analytical thinking in our poetry has been an outgrowth of the culture of Nice-ism.