Why are poets aligned with the left?

I have pondered over this question, and was reminded again about it when the Harriet bloggers had a phone conference recently, and some kind of anti-Bush or anti-war entendre that was uttered by someone produced among us a knowing chuckle.

Now the answer could be that poets sit around thinking, and that anyone who thinks long and seriously will be led to liberal conclusions—that war is, in principle, to be avoided and that people should be treated humanely no matter what their circumstances (whether old, ill, imprisoned etc.) That wealth should have a reasonable distribution among the populace. Therefore: liberalism is in some deep way correct and true.
Or it may be that poets are aligned with the left because they tend to share the concerns of the poor, or at least the not-rich, having only moderate incomes and job stability, maybe no job stability (as in the blogged-upon case of Etheridge Knight). This would imply that poets share leftist sentiments out of compassion. And that poets are, by nature, compassionate.
I get irked, though, when poetry blindly takes up the cause of liberalism without in some way nodding to the assertions of the other side, the other side being the non-left rest of the world. And when poets are assumed to have common natures (for example: compassionate). There is an assumption that we share the same—is it political? no, more widespreadly social—views. This assumption makes poetry more monolithic than it is, and undermines the (naïve?) hope that some poets harbor about the value of poetry in the social commons. That poetry may sway hearts, however corny a thing that is to say. This is not possible because the right is excluded from poetry altogether.
I wish I knew more about the history of poets on the right. James Dickey, a poet whose canonized work I like quite a bit, I’ve heard tell was a political conservative (this is how blogs spread rumor). It would serve poetry well if the right had a voice in it, so that there would be a challenge for the left to rise to. A counter-song.
Maybe this is why there is not much good poetry written about war (OK: Homer) compared to the bulk of good poetry written about love. Poets tend to lapse into propaganda and polemic when they try too hard to “make something happen,” as Auden warned us. Yet it is a good dream, for poetry to serve the civic good in some direct way,
while realizing that through argument with others we make rhetoric (isn’t that how the old chestnut goes?) That poetry is argument with the self.
I hope poets with more of the historical sweep on this subject than I have will comment.