Comedy in a slapstick or silly form may be of little value beyond making people happy. Happiness is something that society needs though. If we didn't have comedy suicide rates would almost certainly be higher. After a long day of skull numbing work it's nice to be able to take yourself out of the equation and not worry about what goes on in the outside world. This was big business during the Weimar Republic when scores of Cabarets opened in Berlin to capitalize on the people's economic woes. In this sense comedy is worth quite a lot.
Comedy is also a medium that makes you think, or at least some of it is. Satire is particularly useful. This is a form of humor that does make you think. Satire is a genre that requires active participation for it to be funny. In order to understand satire one must be conscious of events outside the humor, and while The Onion might have funny articles for the "politically illiterate" those who are aware of National and International goings on will find these articles much funnier. For those people who understand events and concepts beyond the satire it makes them think about those issues, or at least it makes me think about them. The reason for this being that satire brings into question the topic and criticizes it. By suggesting the extreme of the same issue or by going to the other extreme to make a point about how ridiculous the subject it brings into question how sane the people who actually believe in whatever the topic of the satire might be. Perhaps for some the best way to make them think about an issue is through the absurd, because it really brings into question the various beliefs a person might have in a way that is engaging and fun.
So the value of Comedy? I say that it's worth quite a lot.
We don't live forever, so smile!