I'm really not sure there are a ton of people who go to U2 shows for "the scene." Those days are long gone, unless you're a celebrity and end up in VIP somewhere.Straw man much? If you bought a ticket, you're allowed in, casual or hardcore. But people who are interested in actually watching the show are more fun for me to be around than those who arrive drunk because they're just going for the scene. Doesn't mean I want them banned.
People enjoy shows in different ways, and it's a little silly to call people who night but be rocking out to every song, or who only came to see the Joshua Tree (on the Joshua tree tour, mind you) as not being "fans."
Nobody likes being next to an obnoxious drunk... but that's the wonderful thing about GA. If the vibe in your area is bad or uncomfortable, you can move... as opposed to seats where you can end up in a lame section or next to someone who's getting stoned or drunk off their ass and there's absolutely nothing you can do about it.