The More Things Change--veingloryCelia Hart asks: where did the market come from for erotica and erotic romance? To which I reply... come from? Even limiting myself to just my own bookshelf I don't see much evidence that this is a new phenomenon.
The best thing about grad school was all the erotica we read in the guise of Important Literature. Hell, our prof even warned us with comments like, "Yes, this is literature you read with one hand."
Look at those cool old covers! Looks like you have quite a collection. As for your topic, I think it's true what "they" say -- there is nothing new under the sun. ;-)