I think the important point is why people do art.
They will use whichever function fits best, be they weak or even unvalued, if needs be.
Now, why do some people feel the urge to make art, it's personal to them. Whether one's art is seen as beautiful or not, or interesting or not, is a matter of who's looking at it, so personal too. If you wish to make a living out of art, you need to find the right public, or it to find you somehow. Tho, there's no need to show anything made.
My first drawings were ugly bunnies when I was five, I had to draw stuff for school and that's all I could think of. At six I had managed to become "good" at drawing, mostly by not drawing bunnies anymore, lol. Do I have a natural talent in drawing? I have to say no, only an interest in the visual world and a need for an outlet I could only find through drawing in the past, now I write and it turn into poetry and I'm like wtf, I'm not supposed to know how to write poetry, but then again, poetry was invented at some point anyway.

I'm laughing so much at my ugly bunnies, god were they disgusting. halp.