I think what people really into Rugby and Soccer and the like don't understand is that American Football isn't (and really was never meant to be) a full contact sport. Yes, it contains full contact, but that's only a small part of the game. I read somewhere - and don't quote me on this - that during the course of a 3 to 4 hour Football game, less than 10 minutes of that is time where the ball is in motion. The rest of it is playcalling, timeouts, halftime, etc, where the coaches and players strategize for the next play. It's really more like a game of chess than anything.
People want to compare American Football to other full contact sports around the world, but you just can't. It's a completely different type of game, one that isn't won by which team has the best players, but which team makes the best individual plays as a whole. That's why American Football has about 8,000 rules, while Rugby has like, two. The more rules there are, the more you have to figure out how to use them to your advantage and against the other team.
Football is a thinking man's sport, and I'll take it over Rugby any day.