It's not hard. Elves were Caucasian in the Middle-Earth stories, and Jesus was Semitic in the Gospel stories, because the authors of those stories said so.
That sums it up. Black elves are good in the Witcher. But they're not Tolkien. And pre-show, that (and a swashbuckling Galadriel) was all we had to go on. It was clear that we would not be getting Tolkien, thus the low expectations.
Now that it is out, Rings of Power exceeds expectations. It is a good show, like the Witcher. Both are imitating Tolkien, but not as great.
Kind of like The Godfather Part III.