There’s 0 reason why this shouldn’t be a thing. There are some races that have insane amount of customization options and some that fall super short. Whatever options could be available to any race, give it to them.
WoW really needs to work harder to allow characters to feel unique looking. In this aspect it really isn’t up to par. I get that its an older game, but there’s no reason why we can’t have things like simple height sliders either.