Researches into prostitution always miss the point of recreational sex. If it's legal, it's as nondescript as a social drink, but if it's illegal, it's using drugs.
Apart from moral issues, it's not much different from the combination of a game of golf, shopping something nice, a movie, or going to an art gallery.
Think of it as a mini-vacation to a parallel universe. I need vacations away from my wife. Not so much that she doesn't do things that I like, more importantly, she won't stop doing things that I can't stand. Don't tell me 'let her go' that sort of crap. If she want to leave she is welcomed. I do know the substitution can be a lot worse. Emma and Chanel are so nice in many ways that you don't know they are so screwed up in others.
It's not so much of role play, but in parallel universes anything interesting can happen.
Why people have affairs?
Why people pay peak season price for vacations? Because they have absolute control of the time and place.