How about art that makes you celebrate and appreciate life?  Or art that makes you laugh?  Or even art that makes you change in a positive way?
I believe the only thing art needs to do is to provoke an emotion- and it doesn't matter which emotion.  Great art, in my opinion, is that which can provoke a completely different emotion in me from the person sitting next to me, but that both of us can appreciate and recognize as masterful.  And by art, I could be referring to a piece of music, a painting, a movie, a play, an opera, or even a stand up comic.