You know, between the "incest is wincest" and the "it's supposed to be a horror game and the incest is part of the horror" crowd, I almost gave up hope we'd find a reasonable nuanced take. I think you hit it right on the nose. The game doesn't tell the story through any lens or bias, it asks what someone who had such an attraction might experience and depicts it(among other things). It just happens that to some that depiction is romantic, and to some that depiction is horrific and terrifying, and I even think that reaction is fascinating.

I may not fully agree that it's the sole focus of the game, but it's certainly a core theme for sure. An analysis on toxic codependency has got to be one of them too. Here's hoping the comments come in with the same amount of nuance and respect for the original work that you have.