Why would elves have to be black?
We humans come in multiple colors so to have them all as an option to choose is perfectly fine, but elves are a different race, same as orcs, trolls, taurens and more.
These are fantasy races, I don’t see people advocating for white orcs, black trolls or asian taurens.
I personally don’t have a problem with having more colors to choose from when creating a character, but we also have to accept that some races don’t come in every color of the rainbow, orcs are green, the sky is blue and maybe… just maybe… blood elves are not black, nothing wrong with that.