I would rather be told that directly than have some made-up answer. "You're right! It's because the world needs to be pretty!"
Kind of like, at the beginning of god is Not Great, Hitchens relays a story about a teacher who said that the world is green "because that color is easy for our eyes to look at." Well, no, Hitch says. Our eyes are adapted to the color of nature, not the other way around.
To me, the honest answers are the best answers, regardless of bluntness.