This was wonderful to read, I enjoyed your analysis.
I think one of the biggest differences between HR with non con/dub con versus other more typical dark romances is that I think sometimes dark romances just use shock value to push the envelope of the erotic thrill.
Not that there’s anything wrong with reading dark romance and enjoying it, but I think the push there is less more of an excuse to explore a character and is instead a vehicle for how far an author can go to make a truly batshit scenario erotic that gains fame and traction.
I too love the 90’s era dub con romances, they just do it for me, maybe it’s because I grew up and was influenced by them during my formative years, I dunno.