Interesting idea. I find myself mostly in your camp.
I wouldn't categorize myself as a "life pessimist", but I do often feel that a lot of the problems the world faces are intractable, and that we won't come together to find a solution until its too late. Sometimes, there is not great solution, and "good" and "bad" are very nebulous concepts.
On the other hand, sports are a much more binary endeavor. "Good" and "bad" are a lot easier to measure, and even a short amount of time can be enough to take something utterly disastrous and turn it into to something great. (See: 2005 Saints vs. 2006 Saints) In that way, it pays to be a sports optimist because even though you'll often be dissapointed, its not unreasonable to think that success is right around the corner - unless you're a Browns fan.