Things that come up when I Google "The Why of Art"

"The why of art is a trust question. Faith and optimism are not the gifts of materialism; they are what happens out of encounters with the invisible. Art allows this to happen." - Jeanette Winterson, in an article about Paul Johnson

"Who amongst us hasn't at some point wished for a magic wand to convert an awful situation into the fantasy that we crave? Or maybe just to experience something that is not in the cards for us? . . . Art is generous." - painter Joan Gold, in her blog

And a theory that art exists to enhance one's feelings of security, by Stuart Abbey.