I think the one thing left out here is the idea that Brian Moriarty touched on:

"Sublime art is... the still evocation of the inexpressible.”

To wit: the power of a work to cause emotional reaction is a deceptive yardstick with which to compare high and low art. Similarly deceptive is the criteria of a work's ability to provoke meaningful analysis. Both of those level the playing field too much.

The ability of a work to bring its audience to contemplate the inexpressible is far more decisive a criterion. It's not the only measure of value, of course. It's a goal that much art--high and low--doesn't even try for. But a case can be made that so-called low art never tries for it at all.