I wouldn't call The Real Barenziah an erotic novel so much as a frank account of her encounter (and Khajiit anatomy). That's a very small section of that series of in game books.
I wouldn't mind more frank discussion of things like that however I don't think erotic novels would be a particularly good idea. There's nothing wrong with it in my opinion, but it would attract all kinds of attention from the control freak censorship activists.
I don't think you'll find anything else that detailed. In fact I thought the skyrim one was the censored edition. I know in morrowind/oblivion that part is censored out (the original, summty version is in daggerfall)
Sadly yeah despite knowing it had an M rating they used the censored one for Skyrim. Beheadings? Torture chambers? Those are just fine, but oh my we can't say the *gasp* 'p' word! It's not like all males have them or anything.
Either that or both versions are in the game, which I would be surprised to hear.