[squozzer]

Good points, I'll just add a pinch of comment.

1) Art criticism probably plays a role because it helps define art fashion - e.g. when realistic painting gave way to abstract art, it opened the door to people making millions painting triangles (after 37 years of study) and squiggly lines.

2) G. Calling yourself an "artist" probably works as a pick-up line in more bohemian parts of the West.

3) Supply and demand.

4) I think identity politics succeeds in helping artists and customers find niches. So far it hasn't translated into huge successes in popular culture, probably because marketers try to spin such things as originality. Han Solo is a pansexual? Big deal, Captain Kirk slept with a green alien in 1967.