The answer is simple, it's a niche genre.
Something very specific for a small audience and not everyone will enjoy it because it has a big impact on how the game will be, just like NTR, cuckold, female protagonist, etc. it's just not for everyone and that's fine and it should never become more popular.
The reason I say it's not fine for it not to become popular is because when a niche genre becomes popular it loses its essence to accommodate more tastes. This is what happened to the horror genre in games, it became so popular that now it's very rare to see good horror games, most are totally commercial games made for all audiences (no gore or psychological horror), a trivialization of horror reduced to something very ugly that chases you and jump screams.
You don't want that to happen to your favorite niche genre, it's true that you would have more games, but of much worse quality.