jeanne, thank you for the clarification. I come down closer to your side on this than the 'plot' side. I don't believe plots are necessary in porn stories, but I don't think they're a liability, either. The purpose of porn is to get the reader off, so I checked the box for new situations or devices, but the situation isn't as simple as that. I think AndrewBlack is probably the closest to my position.
Something you sometimes run across is what I call "the laundry list". It isn't a story at all, just a listing of all the things done to some cardboard-cutout victim. Sometimes these lists demonstrate great imagination, but they aren't hot. I need to be able to 'see' what's going on; I need descriptions and adverbs.
I'm a big defender of 'slow' code stories, but once the author is past the introduction, the sex should come hot and heavy, and at great length.