Well, let's operate under the preconception that the game is a strong attempt at a work of art. It deals with sexuality, it's pretty clear that's the central theme.
Now, let's set aside the American dialogue on adult-themes in video games and look at the broader picture for a moment. American attitudes towards sexuality are simply not the same as Japanese attitudes towards sexuality. But the game is about sexuality?! The game might hit a lot of things that are important to Japanese sexuality, it may critique it, villify it, exort it, celebrate it. It might be about a man dealing with Japanese sexual culture.
That doesn't translate well. You either have a localization that changes it to approximate American symbols and concerns and critiques, or you have a localization that assumes you to be knowledgable of Japanese norms; either way you're not able to see the game as it is intended. The game is specific to Japanese culture, so a localization to other cultures might simply not be appropriate or on the radar.
Crying shame tho. I do want this game out here.