Yeah, when I tell people I make CYOAs, a common reaction is "I remember those books when I was a kid!" so maybe even those kinds of books don't tend to be aimed at adults, although I don't see why they shouldn't be (a CYOA of the Game of Thrones books would probably have wide appeal).
What are the pros and cons of marketing naughtier games? I suppose you get a bigger audience, but get cut off from some common places to promote- like Twitch. We put out an 18+ version of the Bunny Hill Horror games. These were fairly mild- only occasional nudity and sex, but they still got banned from Gamejolt when they changed their policies, and only remain on Newgrounds.