Maybe because he paints nice pictures that people like rather than more “cerebral” crap that doesn’t really look like anything?
Mr. Kincaid's "art" is popular for the same reason McDonald's sells a lot of Big Macs: because most people are social retards with the palate of a four year old child. Calling his stuff "art" is like putting a Quarter Pounder on a silver tray and calling it "cuisine".
Fact: Most people are ignorant and have no taste. Good taste has to be trained into a person; it does not "come naturally" except to a tiny minority. In his Nicomachean Ethics, Aristotle points out that a good education consists of "having been definitely trained from childhood to like and dislike the proper things" 1.
This is why the world was in general a more beautiful place back before the advent of democracy, when we had an educated, worldly cultural elite setting the tastes of society by fiat. In today's America, however, "good taste" equals "whatever gets the suburban white trash hot". Thus the popularity of Dancing With the Stars, Lite beer, car racin', and other brain-dead delights: in Amurrica, we don't need no stuck-up city slicker with a funny name tellin' us whut a purty pitcher is saposta look lahk. "Yew ain't no better'n me!"
This is why today's most popular TV shows, movies, fashion trends, and music are so bad -- because our culture no longer believes in training children to recognize excellence. Instead, we revel in our schlock, and get all indignant when someone points out that the stuff we think is caviar is actually dog crap.