The information from my wife's sister, who has attended a number of these type of parties is that you seem to be correct. The logic is that that as far as the bride goes there are four things at work; First the alcohol. That of course puts everything on a whole different level. Next the, "One last fling" rationale. Third the "Dare" or "The least I could do since you've all spent this money on the stripper" The bride either doesn't want to have the rep of being a chicken or she figures that she'd disappoint her friends who spent their money if she doesn't. Last is the whole anonymity thing where she feels what goes on here stays here.
Much more interesting I thought, is what else she said. That is that the group who really seems to get laid as much are the Mother-of-the brides, aunnts or anyone else who is generaly in that age category. These women tend to be divorced and unattached and looking, unattached and very aggressive or attached but their relationshio is on rocky grounds. According to her, these are the REAL wild women who come dressed to kill and leaving no doubt what they expect of the occasion. In contrast to the bride, who might give a little head in front of everyone but if they do get laid goes off to a private room later, these are the women who will be willing to take a fucking on a pool table or get bent over a char in front of everyone. Something to think about next time you're at a wedding and looking at the Mother.