I think it is inevitable that re-entry will stop at some point in the near future. People going in and out of a stadium represent a security risk. Somehow it hasn't happened yet, but at some point there is going to be an incident at a stadium that prompts all leagues and schools to end the practice. It's hard enough to quickly but effectively screen 50,000-100,000 people once... having to do so multiple times is asking too much.
As for me, I never leave. I get to go to maybe six or seven games per year. I can hang out with family or friends virtually any other day. If I'm going to spend thousands on donations and tickets, it's not going to be so that I can watch part of a game. I love tailgating before the games, and we often times sit around and knock back a couple more afterwards while waiting for the lots to clear, but during? I just don't see the appeal. To each their own, but that's just not for me.