I'm a nerd. Chess club. Picked on. Etc. And I found that I really enjoyed American Football in high school. I wasn't any good at it. I was third string. I got flattened a lot. But what intrigued me was the complexity. Sure, there's some mindless violence at local levels, but above that, incredible sophistication and elegance at the macro and global levels. The plays and counter-plays themselves are incredibly complicated, and when you watch college and pro games live or on TV, you really are seeing two coaches playing a game of chess against one another. Spend some time in a college sports forum and watch with what detailed analysis sports nerds pick apart the plays, the strategies, etc.
And I found that the same was true for just about any competitive sport. I spent four years as the statistician for a basketball team -- the coaches were nerds when it came to things like shot groupings, trends, etc., and the players were always looking for ways to squeeze out just a little more performance -- kind of like overclockers, only athletic.
Your point about the 'tidy conclusion' is pertinent as well, imho. As an example of a violent civil-war rivalry turned athletic-sportsmanship competitive, consider the KU-Missouri rivalry: http://en.wikipedia.org/wiki/Border_War_(Kansas%E2%80%93Missouri_rivalry).
Now, do I prefer spending my spare time playing MW2 over playing club sports these days. Yup. But I think that's just my medium of choice.