Each and every person has a unique perspective of the world. A good artist works to imbibe life to their fullest, knows how critical it is to fine tune their expression of it, and communicate their unique perspective to others.
We have evolved beyond passing information from one generation to another through genetics, or even nurture. We've developed language to pass information and thus created society. Long life has allowed us to build society through multiple generations. Writing has allowed us to share information beyond our life time. And now we find ourselves connected in a global scale, one giant world wide civilization comparable to an ant colony. Now what do we each deem worthy of sharing with the colony? If one has the luxury of not having being required to communicate for the imperative of survival, than it must be for cultural progress.
There's nothing more valuable to share than your unique perspective. Artists work their entire lives to hone their skills well enough to share their perspectives in the clearest way possible.