Hi, all.
Nothing at all wrong with PWP when compared with plotted written porn. But like you also just pointed out, once you start asking (and answering) questions, then the plot bunnies harness up, and the story takes off for places uncharted.
I suppose you could say a similar thing about human life in general. As a rule, we are social beings and sexual activity, like most other human activities, tends to be more interesting when done in groups of more than one. My Dinner with Andre was well-received, both when it came out and today. While My Assignation with Andrea would more likely be the generic “Pornhub Two-Reeler,” it could also be so much more artistically, even while being just as erotically explicit if not more.
While magical worlds, whether JKR’s or otherwise, can have their own unique gimmicks, in the end they still involve people, with all that implies. Some people are boring, and others not-so-much. And imagination can take you and your reader to the strangest places. Imagine that Hagrid is a closet felcher, and that he unknowingly interrupts Professor (Crouch) Moody’s hallway discipline of Draco Malfoy during The Goblet of Fire. Further, imagine that the human transfiguration doesn’t wear off until after Hagrid has enjoyed some mid-morning entertainment. What if Draco liked it? 😉
Cheers!