Here's a nice point from a post on Ron Silliman's blog:
"Do we want every musician to be John Denver? Can’t somebody be Pete Seeger or John Coltrane or Bela Fleck or Meredith Monk? And wouldn’t that, actually, be more interesting? What if you want Lou Reed & Tuvan throat-singing? The world becomes very monochromatic the instant you want the same level of accessibility everywhere."
RS is making this point in the context of accessibility and difficulty in poetry. I would find it more convincing if RS himself were a bit more flexible in the range of poetry he is willing to recognize as legitimate (which is much different than the issue of aesthetic judgment). But it is true that he is responding to an article that is unwilling to accept his poetry's right to exist, so the argument is understandable.