People may bitch about Rem, rightfully so or not, but he's proven that good porn can go together with good gameplay, and nothing comes even close to KP in the rpg/battlefuck category.
You sort of implying that he's the only one (among the only ones maybe) that do a decent job at both the "porn" and the "game".
Having both "porn" and "game" for a porn game is a requirement, not a bonus from the dev. You can glaze Rem for hitting the standard requirement, especially with that 40 buck price tag, which is a premium price.
As for RPG part of KP you are definitely glazing here, the game lacks what defines an RPG game, if not absent, thing is Rem had plans for them, which didnt make it. Like many other things that arent even in the cutting room floor, it become more and more apparent as you walkthrough the game and see the gaping hole (apart from Karryn's).
What we end up with isnt an complete supposed RPG game but a demo, a paid demo of battlefuck.
As for battlefuck, Well Karryn Prison coined the terms and until now while I definitely enjoy it, I cant say it's good for I dont have anything else to compare, there an absent of battlefuck games out there.
That should give you a hint of game development, and of what Rem promised and what he actually delivered, how and why he is "bitched about".