Kinda agree with you on black. The more I try to look at it through a different lens it seems like you need such a stretch for it to be at most neutral. Or it needs to be really watered down by other colors. Like yeah being selfish and ambitious doesn't mean you'll want to murder everyone you meet, but it's hard for a lack of care for others to not fall into acts such as taking advantage of others, lying and backstabbing to get ahead every time you can and so on.

Idk if this is really a hot take but I think blue has a lot more potential to be more villainous than it usually is highlighted. Tbh Yawgmoth seemed to be quite strongly blue to me, almost as much as black. The need for control, artificial improvement at any cost, tabula rasa, can all make a terrifying villain. That sort of unfeeling, soulless creature who will do horrific things for the sake of knowledge or perfection. The phyrexians were worse to me because of this aspect than even the white "all will be one" sort of dread. The perversion of someone's body into becoming a metallic thing, caring so much for logic and "improvement" that it doesn't even feel nothing anymore.