Tolkien abhored symbolism and allogory, and had a far better understanding of the ideas of 'one to one' and 'onto' than you seem to display. He would have been appalled by attempts claim that he was asserting that the Monguls were orcs or even orcish in nature, or at least, to assert that Asian people were more prone to orcish behavior than humanity in general. The claim that orcs are a Turkish caricature has no more basis in fact than the equally unread claim that the Sauron was an allegory for Hitler and the orcs were Waffen SS.
It's true that Tolkien denied that LoTR is allegory. By "allegory" it's fairly clear that he means allegory in the strict sense. But it's obvious that his writing is "symbolic" or "allusory" in various ways - eg the Silmarillion among other matters very obviously deals with the Fall and Original Sin, both matters dear to the heart of any serious and conservative Catholic thinker. And one of the tropes which the LoTR deploys is the threat to Christendom posed by eastern/Turkic invaders.
I don't disagree with you that orcs are expressive, as a literary device, of certain human habits of mind. But I do disagree with you insofar as I think that it
is significant, in reading and understanding Tolkien, to see that he located this study of human moral failing within a racial and cultural group. Not exclusively, of course, as eg Bill Ferny shows. But it's interesting to note that there are no Numernoreans (to the best of my recall) that are orcish in their outlook - even when they invade the island of the Valar, they are motivated by pride - which is, in the right degree, a noble sentiment - and are not aiming at the destruction of beauty and civilisation, nor motivated by the base greed or hatred, in the way that orcs are.
Is there anyway to present races that isn't expressive of 'racialized thinking'?
That's an interesting question. As I said, I don't know enough about sci-fi games or sci-fi literature to answer in relation to that genre.
In fantasy I know that the Earthsea trilogy deals with differences in human race and culture in a way that I would not describe as racialised. (The last two books head off in very different directions, and I'm not really sure what to think about them.) The contrast with, for example, REH is extremely marked. To put it a bitcrudely, Earthsea reads like its written by a thoughtful, historically-informed liberal intellectual, while REH, in his treatment of issues of race and culture, verges on (or actively embraces) the rabid. Lovecraft is another "fantasy" writer whose treatment of human races is quite racialised.
When it is non-human races in fantasy literature (as opposed to fantasy RPGs) I don't have a particular wide knowledge - but given the huge influence of Tolkien on a lot of this I wouldn't be surprised if racialised thinking was widespread.
Why in the heck are we fighting the 'nurture vs. nature' fight in proxy through fictional alien species, and why in the heck would you think thats the only thing the author is interested in when he creates an alien species? Tolkien didn't really even have a bone in the 'nurture vs. nature' fight as we'd normally phrase it in modern terms; as you pointed out he's not really writing about biology or upbringing, but rather a fight between 'the better angels of our being' and our 'demons'.
I don't think it's about nature vs nurture (hence my view that biology is a bit of a distraction). It's about the literary and dramatic representation of cultural differences. Hence the reference to "Victorian anthropology", which (at least as a stereotype) analyses cultural difference by reference to superiority and inferiority ("civilisation" and "backwardsness") and explains superiority and inferiority in racial terms (what I have called "racialised thinking").
Thus, as I've said above, my comment on Tolkien isn't that he takes a silly view about the link between biology and evil, but rather that he uses as his device for exploring (at least one type of) evil a particular racial concept (roughly, the "eastern horde").
