This is a nice little interview with Robert Anton Wilson about the case for optimism.
"The reason for optimism lies in the biological fact that it keeps you happy and busy, whereas pessimism just leads to lying around and bitching. I'd rather keep happy and busy than lie around bitching, but I know this will not convince those who really like lying around and bitching. As Nietzsche said that optimism and good health always go together, and so do pessimism and morbidity, in the medical sense of the word."
So- I'm coming to the conclusion that it's less about the way things are, but rather the way they could be. So there is a certain amount of malicious gratification in being a misanthrope, and it's certainly easier than being an optimist- but it gets pretty boring- and buys right into the game plan that you are bitching about in the first place- ergo- is stupid.