What does? That Blizzard hasn't provided more hair colors and styles to Void Elves yet?
I mean... allied races weren't supposed to get much focus as far as customization is concerned for Shadowlands launch. They told us back at Blizzcon that core races were the only ones getting focused on at the start. That they gave Void Elves the skin early (which is a straight up copy and paste that required little to no time or effort on their part to do) was a very nice surprise. Hair is another matter though.
While they could copy and paste all the Blood Elf hair styles to Void Elves, I think they may be trying to avoid that and give Void Elves something different, even if it's just variants of the Blood Elf hairstyles (like several Void Elf hairstyles already are). That takes time... time they don't have available as they put the finishing touches on Shadowlands to have it ready for October.
As far as the hair colors go, they actually can't just copy/paste the Blood Elf hair textures to Void Elves, at least not without doing actual work on them because the Void Elf hairstyles have to contend with the tentacles on some styles and the hair ornaments are different from the ones Blood Elves use. That stuff is all part of the hair texture files. Again that takes time they can't spare right now.
That's not petty to me. That's Blizzard prioritizing the launch of Shadowlands with the features they talked about at Blizzcon. Allied races will get their turn for some focused customization work. Consider the skins Void Elves are getting as an early sneak preview... a preview I might add, that is still using the Blood Elf underwear because they still haven't been able to devote the time necessary to update them with the Void Elf underwear.
It's crunch time for the devs and they are going through it during a pandemic which requires many devs to work remotely. Give them a bit of slack on this, especially since we weren't supposed to get much of anything for allied races right now. That we got this much for launch is a gift in my opinion. We should be grateful and appreciative.