The only anal pleasures I've ever admitted fantasizing about are those of being pegged by a hot MILF.
Anyways, it's a mixture of relatively few good metal shows nearby, and hesitancy to go to an area where people that mosh and act like belligerent assholes exist. Wanted to see Slough Feg a few years ago, but I was too young at the time.
In my opinion, you should go enjoy yourself despite the possibility of assholes. They are everywhere anyway.
I go to a lot of thrash shows and it's even rare to see a true asshole in a moshpit. Those guys that are truly pissed off at the world and want to hit everyone. I see one of them in maybe 5 shows. A lot of people in moshpits are just having fun. If anyone falls down they get helped back up immediately. No one hits in the face, body only. It's a good clean way to let out some aggression without any permanent injuries or anything.
That said, moshpits can be avoided entirely if you just want to see the music. Just hang towards the back. Although I've been at venues so small the moshpit took up the entire floor. If I don't feel like moshing those days, I just brace myself up against a support beam or wall, so even if they run into me, they're hurting themselves more. Or you can dodge and they hit the wall haha. There's always a group of people who are just there for the music. It's totally fine to be one of them.
Tbh I see more violent moshing at big 4 type shows than at underground shows. Underground shows are better in so many ways.. people are nice, you can actually get up close, you can meet the band/get autographs, the music is better..
Act to avoid if you don't like moshpits: Havok. Haha, the pit got a little chaotic at that one.
Tl;dr Most shows have 3 layers: people up front headbanging, people in the middle running into each other, people in the back just listening to the music. You can hang back there.