I read a very good book recently called The Formula by Albert-Laszlo Barabas. He says you can equate quality and popularity in situations in which performance is clearly measurable. But in cases in which performance is not clearly measurable, you cannot equate popularity with quality. If you look at tennis players, you find tennis players who win tournaments and difficult games are more popular. So quality and fame are closely correlated in a field in which performance is measured as tightly as professional tennis players. As you move to things that are less quantifiable in terms of performance, like modern art, your networks are going to be more important in determining popularity.
(Note to self: find that book.)
I think literature also falls into this category. Much of taste in art is subjective, but also influenced by others who make a good case for something. Most of why I get interested in something is because a) I bump into it on my own recognizance, or b) someone else who has highly specific and well-articulated tastes, like Rexroth, is able to convince me that it's worth the time. What with there being so darn much out there to begin with, any filter — especially one that seems closer to addressing my own needs and sensibilities — will be welcome.
I also think any attempts to develop "objective" criteria for measuring the performance of any art form is doomed to fail. Box office success, for instance, is a lousy index for both quality and cultural relevance. Look how many people bought tickets for Avatar, but who actually cares about it? Apart from James Cameron himself, pretty much nobody. They were buying tickets to a carnival ride, and I suspect most of them knew it on some level.
Most of the stuff we care about five or ten years down the line didn't make much money the first time, for the same reason many of the winners of big-name book prizes don't seem like much in retrospect. Success, however you measure it externally, isn't the same thing as accomplishment.