I do see your reasoning, but I don’t really feel the vibe of high elves being neutral as a big draw.
Earthen might look similar to dwarves on a very generic level, but the similarities end there. They are culturally different, their appearance beyond body shape is different, their history is different, so on and so forth. You won’t look at a dwarf and an earthen standing next to each other and have a hard time telling which is which.
High elves aren’t that. At least, they are not supposed to be according to the lore. The difference between a high and blood elf is mostly political and eye glow. They are culturally the same, visually the same, so on and so forth. There isn’t a distinction really worth following through.
Don’t get me wrong, I think y’all should get your high elves for the Alliance. But they’re superfluous for the Horde, and not as big of a draw for a whole expansion’s selling point.
Now playable, neutral Naga? That’s a sell.
Naga are, ultimately, mutated elves. In a Grand Unified Elf system, they would be a reasonable inclusion. Have a rebel band who are fed up with Azshara and want to help stop her from blowing up Azeroth and you have a story hook for their inclusion. As former highborne, they fit in with Horde elves (Nightborne). Tyrande has already shown a willingness to work with Highborne and after the issue with the Nightborne, she might be more willing to be more diplomatic, and she’s about as opposite from Azshara as an elf leader could be, so you have the Alliance-side naga hook.
But we’re already getting neutral Earthen which while not really Alliance-associated, they certainly look Alliance associated, and have no history with the Horde, even as enemies. So players tend to look at them as Alliance-like.
Going with the expansion after that by making an actual Alliance lore race suddenly also be neutral is just giving Horde fans the finger. We don’t need another Alliance-ish race stuffed into Orgrimmar. We need another monster. Nagas could be that monster.
And really, a lot of the issues with playable naga that were brought up in the past are resolved. Pants not showing? No big deal, dracthyr already do that. Mounts are a problem, but you can just have the tail curl up or something. However dracthyr tails are handled, just more and bigger. Throw in a visage-like passive to look more elf-y and you’ve got a win.
Again, I want you guys to get your high elves. I really do. But we don’t need to also have them on red side.