Is there any particular reason Dracthyr have such limited Visage skin colors?

It feels like they should at least get to choose from Night Elf/Nightborne colors as well to help set them apart; Seeing as how they're sort of just generically "elves", they could at least be able to pick from any of them. It also feels kind of unfair seeing Ysera on the loading screen, as the only aspect with a completely unobtainable appearance, unlike the others.

Short of just letting Visage forms be any race, they could use more non-human(/belf) tones, and it doesn't seem like it would be a particularly difficult addition.