Not sure what point you are trying to disprove with the first point. Sorry. Highmountain and Tauren are both Tauren. Nightborne and Night Elves are both Elves. Trolls are Trolls.
I am focusing on the most important issue, the issue that everyone keeps sweeping away, possibly the reason High Elves will never happen.
The implementation is important. Dark Iron dwarves were already part of the Alliance and not part of the Horde. No other race was a palette swap for Dark Irons from the Horde. It's not just that High Elves are in the Alliance. For what little everyone can agree on, that is one I think we can.
The problem is implementing them to being playable. To be happy, the pro crowd would have to find something between a 5 and 6, and as I have said, anything beyond a 3 is going to experience major pushback.
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Blood Elves are High Elves. Sorry if that triggers you.
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Blood Elves were fel corrupted. That was one of the issues that originally caused a split in the race. After the restoration of the Sunwell, that point no longer exists.
and Void Elves are Blood Elves, that delved into the void. Again, sorry if that triggers you.
No one has yet to come up with a reasonable compromise for implementing playable High Elves.
Blizzard has made clear that a palette swap is out of the question (Option 6 on the continuum)
Most people have dismissed giving Void Elves customization's (Option 4)
If there exists an Option 5, I would love to hear it.