You seem to be the one who is guilty of a fallacy.
Why does JRRT reach for those tropes to characterise his "inherently evil" people? Because those tropes are part of a repertoire, grounded in racist ideas and a more broadly racialised worldview, that is readily available to him.
You also mischaracterise what he says. He obviously does not say "imagine typical [East] Asian features, but then twist them, make them distorted, less human etc". The word human does not appear in what you quote. He appeals to (what he takes to be) European reactions to certain non-Europeans.
And what fallacy would that be? That’s a weak “no you” retort.
The genetic fallacy means (as demonstrated with the wedding ring example) that even if you could objectively prove that every fantastical monstrous trope in D&D had unequivocal, racially motivated origins, it has little to no relevance to how these creatures are utilised in the game.
Tolkien’s quote around “degraded and repulsive versions of” (not actual baseline phenotypic characteristics ) suggest a twisting from the norm. Twisting from a human norm would make it less human in appearance no? He is trying to draw a distinction away from Zimmerman’s imagining of beaks and feathers. And again, I do not subscribe to his language used at all.
Certainly, his world view was characterised by his context, as is everybody’s. Certainly, his words would be called out were they uttered today. I would happily do so. It seems you are happy to acknowledge the setting context yet condemn him with a modern lens. Which is in itself problematic because then all literature prior to the last decade must be condemned as it is tainted by world views that are not our own.
If you could pick any historical progressive person to meet, they would still hold values that would shock or discomfort our modern sensibilities. Because it needs to be contextualised. Ie, are their views extreme from their contemporaries?
If we are to condemn Tolkien for his letter here, then surely he should be applauded for earlier letters.
For example, Nazism did not spring up from no where, anti semitism had been rife in the western world for some time (and unfortunately persists to this day). Tolkien’s pro Jewish rebuttal to Nazi questions around a possible Jewish heritage should be acknowledged in attempts to question how prejudicial he was in relation to his contemporaries.
Relating it back to his Orcs, they are more biblical for his sources. His Elves are akin to angels, Orcs, corrupted versions of those, echoing a fallen angel trope.
Possibly the only explicit Orc based on a real world subculture would be the Games Workshop Orc based on English football hooligans.
For anyone concerned, as an Englishman, you have my blessing. It’s all good.
