The question of difficulty is one with which I wrestle constantly. I want to communicate in my poems—I can’t imagine writing without the desire to reach someone (nor could Paul Celan, a very “difficult” poet)--but at the same time I don't want to pander, and I don't want to do or say things in the conventional or expected ways. No one should set out to write difficult poetry (that’s just to provoke), any more than one should set out to write easy poetry (that’s just to pander). One should follow the lead and the needs of the poem at hand.
I don't think that any good poet intends to be difficult (or that any good poet intends to be "easy"), but I also think that difficulty is sometimes both unavoidable and necessary when one is trying to get at something complex, to say something that doesn't already have an already available vocabulary (it's usually a bad thing when something does have that conveniently at-hand language), or just when one tries to approach something in a unique and distinctive way, which good poems always try to do. T.S. Eliot said that genuine poetry can communicate before it's understood, and that's certainly been my experience. If one feels the poem, the conviction of its language and its emotions, as I felt “The Love Song of J. Alfred Prufrock” when I first read it, that can lead to understanding—at least, that's the only reason one would want to understand it, the only reason one would care. It's like the experience of listening to music: we don't necessarily "understand" it, but we immerse ourselves in it and it affects us.
Much of what people say about "accessibility" is very condescending, as if "ordinary people" (whoever they are—certainly not us) are incapable of grasping or appreciating something complex, as if they're too dumb to connect with anything that has any nuance. I don’t think that poetry should be difficult, but I do think that it should be as complex as the world is. Poetry should live up to, enrich and illuminate the world, not simplify or flatten it out, which too many poems of all camps do (and probably always have—despite the perennial narratives of cultural decline, good poetry, real poetry, is a rare thing and always has been).
These days there is too often a cultural leveling, in which the notion of "equality" means that everything must be "equivalent," and all cultural products must appeal to the lowest common denominator—which is also highly patronizing, assuming that "the masses" can neither be interested in nor understand anything complex or challenging. This kind of thinking seems to function largely to displace desires for equality and democracy from the social realm to the aesthetic: a bracketing not everyone can afford. I have heard people assert that writing complex poetry is equivalent to writing in Chaucerian English (as if complexity were something obsolete which we must move past), and that difficult poetry is "unfair to the mental capacities of non-poets." Such condescending attitudes would discourage anyone from trying to read poetry—no one wants to be looked down upon.
The popularity of crossword puzzles, sudoku, video and computer games, and even convoluted television programs like 24 and The Sopranos indicates that people do in fact enjoy mental challenges. But, when people think about poetry (which is not often), and when they think of it as other than Hallmark card verse, there is the assumption that poetry is more difficult than other things (though many television commercials are more difficult to "read" than most poems), that only egghead intellectuals can enjoy or understand it, and that it has no "relevance" to "real life." That "relevance" (or "life," for that matter) could be a much broader category than simple and immediate identification is rarely considered.