Here's a link to yet another study showing that making and even viewing "art" -- meaning stuff in museums, not Hollywood movies -- is strongly correlated with happiness and well-being. This study in itself is not very impressive, but it fits with many others showing such a link. Tortured artistes are a stereotype, but in general people who regularly play an instrument, paint, sculpt, or write are happier and feel better about their lives.
Two of the human pursuits with the least practical use -- art and religion -- are two of the three that correlate most strongly with happiness. The third, being with friends, has obvious evolutionary value, but on the other hand it works whether or not the friends are doing anything "productive."