NTR by itself doesn't do anything you said. It's just a type of content. You can have jealousy, drama, gangs, and whatever else you want to conjure without NTR and the tory will flow all the same.
Using Game of Thrones as an example is poor since GoT doesn't really have any unless you count Shay and Tyrion was better off.
Sex VN games have "this problem" you speak of because the vast majority of developers aren't good writers. It's writing that makes games stand out. They either lack the chops for it or they aren't interested in being some kind of porn Shakespeare because they just want you to support them financially while you occasionally bust a nut.
No amount of bad endings will make WiaB great. No amount of William getting cucked, no amount of cum Miru chugs, none of it will make the game last. Only the writing will. Can Ocean tell a good enough story to keep money flowing and the project running until it's completed over the next 10-30 years? Time will tell. (though probably not without SG

)
This post makes me sound like I'm anti-NTR. I'm not. I'm pretty indifferent to it all things considered. I just don't accept the idea that NTR is going to somehow make WiaB better. It's optional content for the niche.