You know, at least for Benny and me, I think our interest in anal play is based more in the symbolism than what it really is.
Butt sex is the only remotely mainstream sexual activity we haven't done yet. It's forbidden. Supposedly painful and dominating. Supposedly the greatest and darkest of pleasures. It's the Last Frontier.
But when you get down to actually trying it, the chief objection isn't "oh my god the pain" or "oh no the pleasure is too intense," it's "I think I might poop."
Yes, no one said traversing the Last Frontier was easy.