I think all opinions should be respected as long as they come from a logical place.
As an example, if there were, say, a massive wave of players asking for Charr from GW2 to be made a playable race in WoW, I don’t think I could really support that. Charr aren’t from this franchise, and any knock-off we got would always feel like a knock-off. Arguably GW2’s Charr would fit in well with the Horde in terms of mentality, culture, and history, but that doesn’t mean they’d make for a logical inclusion to World of Warcraft’s roster of playable races.
There are races within World of Warcraft I would argue wouldn’t make much sense as playable, either. Take murlocs for example. There are players who would love to play Murlocs, but they aren’t likely to be interested for any reason of immersion or lore, and more because they just like Murlocs and think it’d be hilarious to make a Murloc Guild and just swarm the opposite faction in battlegrounds with macro’d, “MRGRGLRGRGLRGL,” in /yell.
High Elves are a tricky subject. Their additional arguably ruins the immersion of Horde players, though to what degree is questionable. The conflict between Blood Elves and High Elves has featured through many expansions now. Really the biggest issue is how, right now, High Elves and Blood Elves are identical, and concerns over how High Elves could be made visually distinct from Blood Elves as to avoid ruining immersion.
It can be done, of course, but no matter how different they are, some players will feel like their immersion has been ruined. Granted that’s how some Alliance players currently feel, not having been able to play an staple race in the Alliance faction for so long.
It falls to Blizzard to find a way to add High Elves with enough differences to prevent ruined Horde immersion, while providing the Alliance with the race they’ve been lacking for the game’s living history. It’s also up to Blizzard to take up that challenge or not, though if not, I think they need to provide a thorough, well reasoned explanation that doesn’t devolve into meme status like the, “The Horde is waiting for you,” comment did.