living on a street with 8 contemporary art galleries I can say that 90% of contemporary art sucks. It's just like startups, 90% of them fail. But people who love startups or art keep making more regardless.
I think a lot of the irritating attitude is the support of people who all do the same thing. Same way when your friend makes a new web app you're not going to say it sucks even if it does because (a) they're your friend and (b) you are going to want moral support for your next web app at some point.