Which villainous race(s) are next on the chopping block?

[Sigreid]

The issue is, books like the Monster Manual and Volo's Guide then present various "Others" as monocultures of evil and destructive behaviors. Exceptions are allowed, but in the vein of "one of the (G/)good ones" that characters like Drizz't fall into.

The logic winds up something like:

"These X are ok to kill because they are going to rob/harm/kill/eat/enslave the PCs and/or those the PCs care about."
+
"X culture universally promotes robbing/harming/killing/eating/enslaving the PCs and/or those the PCs care about."
=
"Therefore all X are ok to kill (unless they demonstrably prove otherwise; guilty until proven innocent)."

The middle step is what needs to be taken out.

Doing so has been done before too, even partially in D&D. Look at Eberron, where all humanoids and even many monstrous humanoids each have a number of distinct cultures, plus prominent multiracial cultures. In the best cases, those cultures are then themselves nuanced and multifaceted instead of being stereotypical monoliths. That just needs to become the normal approach instead of what's been done up to now in the flagship settings (Greyhawk and Forgotten Realms).

I think that's perfectly acceptable for a book like a monster manual that sets a default and even says in it that the DM can change if they prefer. I'd argue that it would be a setting or race specific book that should offer other suggestions more in depth. I mean, in the end the purpose of the monster manual is to give the DM ready made opponents ripe to be fought, killed and robbed so DMs can get on with their dangerous adventures. So, I don't see anything wrong with saying "The default is this race was created to bed legitimate opposition to a heroic party. Or this race was created to challenge and evil party." and get on with it. The reason it was never a problem in the past is we didn't have people with access to lots of other eyes deciding ON THEIR OWN, that x race was a stand in for y real world human group and that's just horrible. In 40 years or so of playing I've never thought the monster races were anything other than monsters that took humanish form so the party could use their stuff and thus benefit from fighting them.