You can place me in the category of people who think a lot of "art" is bunk, but having said that, I have to admit that in this video Elisabeth Sherman from the Whitney explains the opposite viewpoint quite lucidly and persuasively.
p.s. to other bloggers - in recent weeks, YouTube seems to have altered their "sharing" options. In particular, I seem to be unable to download videos at the greater (?650) width that was previously an option. The "embed" link now always defaults to 560x315.