Everyone question about those things, if they aren't explained, its our curious nature
Even in wow people ask why blackrock and dragonmaw orcs are grey and why the dragonmaw have red glowing eyes.
When there is no question, its because we already have answers, like with trolls, we know sand trolls are like that because they live in a desert, we know forest trolls have fur with moss. If we suddenly have a Troll that was RED? people will fucking start to question.
Even in dnd we have that, sea elves are blue cause they adapted to live in the sea, drow elves are purple with white hair because thy were twisted by an evil god and so on
So this isn't not rly a good argument