Art - any form of art - is a weird thing, really.
Consider this: in a world where most creatures spend 100% of their time finding food, mating or rearing the next generation (if they're mammals or birds), we spend as much of our time as we can on something which is patently useless. Something which has no bearing on our survival. Either creating it ourselves, or recieving it - in the form of reading, watching TV, listening to music, playing computer games, what have you.
And we do this because we find it pleasing.
What sort of weird evolutionary pressure has prompted us to watch Dallas? Is my survival in any way helped by playing Sim City? Even Stone Age pottery is adorned with patterns, for no particular practical purpose. They just liked the look of it.
On the extreme end, we have dug up rare metals from deep inside mountains, put them together in intricate forms, thrown them from one dust speck in a universe consisting mainly of nothing very much to another dust speck, simply because we were curious to see what it looked like!
OK, OK, there are all kinds of spinoff effects from the space program and it's paid for itself ten times over, I've worked there myself so I know about this. But this is a rationalization, an argument put forward by people who have primarily emotional reasons for wanting to explore, and who then go out and find rational facts to support them.
We need more useless things in our lives.