Indeed, not to mention blue tents/flags/clothes vs red blue tents/flags/clothes etc whenever Blood Elves and High Elves square off. The colours themselves are more important to the faction divide stuff than the thalassian elf model itself which is already shared between factions since TBC, and considering they're hesitant to let Alliance players even play something that's already on their faction I doubt they'd drop their colour divide just like that. Yeah, transmog exists and can make you look like the opposite faction to some extent, but not really the same thing as the standard customisation options.