They haven't. We've yet to see them in their majestic, but asshole-y glory.
Your previous response to me was already refuted by rumaya2000, so..
No, that's not nearly comparable. DK humans are just humans with a paler skin, some slight indications of being malnourished and bone textures here and there. High Elves are literally just Blood Elves with blue eyes, or rather.. Blood Elves are High Elves with green eyes. You're pushing a biological distinction between Helves and Belves that has never existed for the sake of making your broken dreams to play an Alliance Blood Elf real.