Eh, I don’t think it’s something to be concerned with, provided the adaptation contained internal consistency. Let’s face it, generally authors write what they know, and what’s around them. Since so much of the popular media that’s entered the Western zeitgeist comes from authors in the same sphere, we see a lot of whites-only fantasy, as that’s the culture those authors are coming from, and from a historical representation perspective (which is generally where fantasy is drawing from), that’s what we see. It’s not always the actual truth of the matter, but it’s how history is presented to us, so it’s how it gets recreated and reinvented, even when translated to the medium of fantasy. It also provides for easy shortcuts (hey, this fantasy race is a stand in for Spaniards, this one for Asians, etc.).
Where I’ve seen character visual appearance actually matter in fantasy, it usually has to do with a narrative purpose, and not the actual appearance for its own sake. For example, in LotR (books, not films), Aragorn and Boromir look alike, because they are men from the same stock. It doesn’t actually matter that they’re white, with dark hair and gray eyes. It matters that they look like the same people. Same with some of the appearances in Game of Thrones (again books), but not all. There, it’s important (to some degree) that the Lannisters are blond, because of the gold obsession that people attribute to their people. It’s important that the Targaryens have silver hair because it’s “alien” to most humans. But for the rest where appearance matters (for example, the Stark children favoring Tully blood except for Arya and Jon, or the fact that Robert’s trueborn children look like Baratheons), only consistency with the narrative requirements is important, not necessarily the racial composition underlying that consistency.
In other words - what is the purpose beneath the visual representation, and does that purpose enable broadening the inclusion of varying races when adapting? Because again - most authors write what they know and see, and that’s not a knock against them, but it does mean that representation in classic media is not exactly representation in reality, or representation that will be inclusive.
At least, that’s how I approach it.