I think 99.9% of the crowd were on thier feet in the first 5 seconds and stayed that way right to the end.
Aw man. It's a good thing I wasn't there. If I paid for a specific seat and was forced NOT to use it just to see the stage, I'd be pretty pissed.
Perhaps you need to rethink it as having paid for a specific place. I expect to stand for a least a portion of a rock concert, depending on who it is. Probably not for a folk or blues session but for a punk rock band famous for creating a frenzy, I arrived prepared to be on my feet.
I hear ya though. Last year at Rush, the crowd began to stand part way through the second set. I had an older gentleman behind me who wasn't going to be on his feet. I remained seated so he would not have to fight for a view. I was in a row with a rail and slight drop in front of me, so I was lucky that I could still see most of the stage seated.