I'm not a regular reader of The New Yorker, but if I happen upon it (i.e., if I find it unused in the common kitchen area of the house), I'll give it a look-see. In an article on Van Gogh, there's a digression on Gauguin—who, like Wagner, happened to be a generally terrible man who made extraordinary art.
[Bernard] Williams points out that Gauguin's is a prime real-life case where doing the wrong thing—abandoning your wife and children and betraying your friends—appears to be morally justifiable, since the art made was, as it happened, great. Moral assessment, Williams suggests, has a strong component of sheer contingency and chance. You run a red light and no one notices; I run a red light and hit an old lady and I'm the worst guy in the world.
Gauguin is the original of the type, of whom Picasso is the most famous realization, of the artist as gambler—the solitary risk-taker, indifferent to anyone's welfare but his own and therefore capable of acts of independence and originality unknown to timid, orderly, nice people, acts that thrill and inspire new acts a century later. It is the goal of that kind of modern artist to run the red light and hit the old ladies—the old ladies of custom and convention. Where art since the Renaissance had attempted to limit luck in a system of inherited purpose and patterns, modern art demands that you press the pedal as hard as you can, and pray.
So that's what's wrong with modern art: the urge to upset people enough to be remembered for it by future generations, and the rejection of "inherited purpose". The great myth of modern art (of modern man, come to think of it) is that the artist is an autonomous individual whose actions, however abhorrent, may be justified by the acclaim of people unknown, or unborn.
It is far to easy for me to sit back in my armchair and complain, though. Let me talk of something I may be a bit more qualified to discuss: music. We see the same type among composers, as well: Wagner, Schoenberg, perhaps even Mahler(?!). But the world would be a far worse place without the music of these men. (For those uncertain about Schoenberg, I suggest you try his Gurrelieder, or Verklärte Nacht. Gorgeous pieces.) Would their great art have been possible if these men had not been egotistical bastards? I don't know.