This happens with every single fantasy property, it seems; people remember older TV or film adaptations cast entirely with whites (because until recently, Hollywood discriminated with wild abandon and none of these fuckers minded) and come away with the false impression that this whitewashed world was "in the books", and will insist on that interpretation even after it's been pointed out to them that the text of said books establishes no such thing. Indeed, fantasy authors are more likely to embrace race-diverse and gender-diverse interpretations of their work than are authors in most other genres. If you understand the entire fantasy genre as a kind of pageant to the superiority of European skin tones, go wild, but the authors of the genre are not likely to be on your side in this. In this particular case, though he certainly had his failings and Lord of the Rings in particular has been the target of some severe and justifiable criticism on the issue of race, Tolkien was NO friend to Nazism or the misguided notion of a pristine Aryan race, which offended him on both a personal and professional level as a philologist. I think it is fair to say that he would object more to those "championing" his work in a case like this than his detractors.
But even if that isn't the case, it's hardly an excuse to endlessly repeat the sins of the past on into every future adaptation. Such a position is morally bankrupt and financially suicidal. Fantasy will mean very little to anyone if it becomes the exclusive province of the socially regressive, who are not its most frequent consumers anyway, even if they wish through decibels alone to give the dubious impression that they are the most passionate. I used to moderate at a fan forum for Lord of the Rings properties, and while this was certainly a divisive issue, it was far less divided than the question of whether Balrogs had wings or whether Frodo and Sam had a thang. Just as in daily life, the pro-racism faction within that fandom was tiny, bitter, aging, and loud. Most Tolkien fans are more embarrassed than proud than proud of the orientalist and royalist tropes regurgitated in the second and third books, and keen to mend the wrongs of a less informed generation.