This idea was already proved false and flawed.
You can't focus on something that will actually excite "only" 30% of your playerbase, since its the amount of people who play blood elf and human.
Even if not, its not a good way to develop a mmo.
..you just proved yourself that lorewise they can be anything they want.
there is no such thing as "it makes sense to force everyone play with elf or human because its the preference of the aspects", its us who is going to play, the choice should be ours.