Few things,
1. I don't disagree with your point. There are a lot of crappy (usually jrpg) ntr games out there, and I also happen to play them. My opinion may also be biased off the fact I'm not a fan of hard cucking, like the mc knowing his girl is cheating and loving it. I much prefer him not knowing/slowly finding out. I also much prefer having a say in the ntr side of the story. I don't think most ntr games would benefit from a non-ntr route, but I still think a lot would.
2. Thanks for the game mention. I tried it, and GF tapes was fun.
3. I have to disagree on your point on GF tapes. In fact, I think it sort of proves my point in a way. From what I see, the game rn has three routes. Cuck route, confront route, best friend route. Confront route is essentially the anti-ntr route, (even though you still get ntr'd), and I think the game would've much worse if they didn't have it. My entire point is it's kinda annoying when easily avoidable/noticable ntr is happening beneath an mcs nose, and you as a player can't do anything about it. That's not the case in GF tapes, they let you confront and evolve. I think if your mc is intellgent, and isn't just some massive cuck, he should eventually gain the option to do something about the ntr.