I don’t know. I don’t think anyone knows. But I also think you’re asking the wrong question. It’s not that the villains aren’t allowed to be evil. It’s that they shouldn’t embody bigoted tropes that were used to justify discrimination against real people. For another example of a monster inconsider in need of changes for sensitivity reasons, the Yuan-Ti. Yuan-Ti are Aztec-coded snake people that live in step pyramids in the jungle and sacrifice people to evil gods. I’d argue that’s insensitive and pretty racist. The human sacrifice of the native Mesoamericans was greatly exaggerated by the Spanish colonizers like Cortez specifically as a justification to conquer and enslave them and force them to convert to Christianity on punishment of death. To make monsters that embody colonial propaganda used to justify genocide seems bad and gross, to say the least. Imagine if D&D Goblins were based on Jews in Nazi propaganda. The problen wouldn’t be that they do evil things. It’s that they do evil things in a way drawn from real life propaganda that was used to justify the discrimination of that people. I would be calling for the removal of that depiction of Goblins, like how I think Aztec Yuan-Ti is a problem.
Does that mean that D&D monsters shouldn’t perform human sacrifice? That the concept of evil deities shouldn’t exist? That fantasy cultures shouldn’t wear clothing tied to real-life peoples? Maybe. Or maybe it’s an issue of implementation. Maybe if the Aztecs were more based on the ancient Mesopotamians they wouldn’t be a problem. If they prayed to idols they thought their gods physically resides in (possibly Eidolons), had Mesopotamian Ziggurats, and more desert theming. Or if the Shulassakar were added to base D&D, so there’s a good Yuan-Ti faction with Aztec flavor, that might make not fix everting but make it better.
I don’t think making it so hags can be male fixes them. That just turns into equal-opportunity ageism. Which I guess is slightly better. I don’t know how you could fix them.
This is a problem for more than just the villains (see the 5e Hadozee controversy), and it’s not a “the enemies kill people, that’s so problematic” (Zombies and Owlbears kill people in D&D all the time and no one complains about that being a sensitivity issue). It’s less about “what the monsters are allowed to do” and more “what the fantasy creature represents.” Hags represent ageist and sexist tropes. Yuan-Ti represent colonial propaganda about the savage human-sacrificing natives. The original 5e Hadozee’s backstory was uncomfortably close to colonial propaganda about the colonized Africans being apes civilized by their oppressors.
It’s about depiction, not action. Real world issues being echoed in fantasy is the problem, not the fact that they’re evil. Also about punching up versus punching down. There’s a reason why Ixalan’s depiction of the conquistadors as vampires is okay, but I don’t think evil Aztec Yuan-Ti are.
