I could give you a hundred different metaphors on what art is, but then that would be idiotic. Trying to explain what art is is just stupid, because one has to use words, a flawed medium. I think people should think of everything as art. Anything can be art if it really wants to be. An upside down urinal. A fifty dollar bill. Just call it art, and it is. I'm not being sarcastic. It's art.
I don't think the artist needs to explain his art. I don't think the audience has a fundamental right to see art that they can understand or identify with. However if something is too obscure, or people just don't understand it, they won't like it. Or they might, you never really know with some people, but my point is that anyone can call something art. It's up to the people paying for tickets to a museum to choose what gets promoted as art.
It is wrong, wrong, to say that something is not art. I think it is mean to say that people have an egotistical agenda, or are just stupid to think a urinal so important. They can think what they want, and so can you. It's the beauty of opinions, anyone can have them. I think rarely is someone making strange art because they want money. There are more sane ways to make money. Usually people have some meaning. Piss christ had a meaning.
Art can be obscure, and hard to understand, but that doesn't make the artist an asshole. Shakespeare wasn't an asshole for using big words. People do what they want to give their life meaning. If you don't like it, look away.