When the same amount of time, if not more, is spent drinking/tailgating for the game rather than watching the game, violence/harassment/assault is going to be issue. You want to get rid of the animosity that opposing fans are shown when visiting a game, than you have to get rid of tailgating.
And I'm addressing the situation as "boys will be boys." I completely understand where you're coming from. Ideally, you should be able to bring your child to any sporting venue. But, times have changed and it's simply not that way any more, football games especially. The game has become second to tailgating. But like I said before, if you want to address this issue, by all means . Unfortunately, violence upon opposing fans has become something of the present and I don't see much change.