Colleges have the biggest stadiums they could afford at the time they started the project to build those arenas. College football and college basketball tend to attract the college alumni and make excellent opportunities to invite said alumni to help out the old alma mater. The larger the arenas, the more folks they can accomodate at once. The more they accomodate, the better their odds of badgering the alums to donate yet another pretty penny to the college fund.
I believe the whole point of college football, basketball, hockey, baseball, - and even tiddleywinks - has been lost. Originally they were excuses to have kids exercise. But then the "rivalries" started up and things escalated. It might be an unavoidable part of human nature to want to associate, even indirectly, with a team who can make short work of their hated rivals.
Which is why I actually watched the New Orleans Saints try to lose a game against the Atlanta Falcons this Monday. But somehow the Saints managed to hold on to that one. Yes, I admit it - I cheered them on. It is so rare for my home town citizens to have something to brag about. This year, the Saints actually are winning. At the end of the season, odds are pretty good that they will have a good to maybe even decent won/lost record. In which case, half of the citizens of New Orleans will party themselves into a cold stupor. I won't mention the SuperBowl, which is usually a lot of hype anyway. But if the Saints DO make it to the Superbowl, New Orleans will effectively shut down for a day or two.