High Elves on Alliance has basically been the most requested player feature since vanilla.
Since someone might challenge that assertion, here is a wow developer stating it: https://www.youtube.com/watch?v=HyDQF0SisAA&feature=youtu.be&t=4m13s
When they did customization in Shadowlands the art director said:
" According to a dev interview Ion gave several months ago, Blood Elves were originally unintended to have blue eyes in Shadowlands, but later on that decision was reversed following team discussions. If the art department was involved, what was the reasoning that led to blue eyes being added for Void Elves and Blood Elves?
Shadowlands Zones, Covenant Armor, and Character Customization Interview with Art Director Ely Cannon - Wowhead News
This is another place where there was a race, High Elves, in the game which hadn’t really been represented on player characters. Blood Elves were the closest, but had felt green eyes. It was an opportunity where we had a number of elven races, and we could tie it back to their roots, letting players choose where they want to align and what fantasy to play out. We did have a lot of discussion about it, ultimately we might do more in the future, but for now we’re providing the option to have a few High Elf customizations available."
But thing was they didn’t give Void Elf players any normal hair color options… and then they announced they weren’t doing customization options. Pretty upsetting stuff.
So now they’re adding natural hair colors.
There are still issues. Mouse over says, “Void Elf.” voice files are, “Void Elf.” and entropic embrace procs…
There are also few hair options.
So… Void Elf requests will likely continue for a long time.
But due to WoW developers stating it’s the most requested feature, I’d imagine it’s being well received.