The skin tones alone are enough, really. If trading away light hair colors is all it takes to not have to live amongst the dirt, smog, and spikes of the Horde, that seems like a pretty good deal.
I mean, if you go in game, the race tag on certain NPCs says “High Elf”. Because they’re High Elves. Just like Blood Elves have “Blood Elf” as their race tag.
But when Blizzard refers to the people as a whole, they use “Elf”. Not “High Elf” or “Blood Elf”. Simply Elf. Because that is the base of what they are.
What things are listed as in the game’s code isn’t all that relevant to the actual written lore.
Also in a biological sense Elf would be closer to the Genus. A Night Elf is not the same thing as a Blood Elf. They might be related, but they’re not physiologically identical.
The groups calling themselves High Elf and Blood Elf however, are.