This is no one else's issues but Blizzard's. It's already known they could've just added High Elves in the first place and avoided all of this.
It's their mess they made and it's theirs to clean up if they wish to. Even if they didn't want to clean it up, even if they don't see it as a mess (I'd find that surprising), Void Elves are still regarded as the most ass-pull race ever to exist among the community at large.
Even among those that don't want High Elves to become playable. That's saying something powerful if even the opposition to the High Elf community can at least agree that Void Elves were such an unnecessary ass-pull.
Especially as Blizzard continues to place Alliance High Elf NPCs among Alliance troops and citizenry, they know what is meant when someone is asking for a High Elf. The whole incredulous, "What do you mean High Elves? The Blood Elves are High Elves right there, go play em!" is just a red herring to not own up to the mess created from adding Void Elves (who using the BE is HE logic can also be used on VE is BE is HE too then - which sounds incredibly stupid and reaching). Nightborne are Night Elves too btw.
Appearance is the "easiest thing" to change, look at Highmountain Tauren. Slap on Antlers and some Tattoos instead of Horns and no tattoos and boom "new playable race."
The lore of the Alliance High Elves already is different from Horde Blood Elves. When they diverged as a group (even in name) they also diverged story-wise as a people.
High Elves have worked among Alliance troops since TBC, showing vile hate for Blood Elves. In Wrath there were High Elf mages among the 7th Legion troops and of course we were introduced to the magical city of Dalaran ran by Human-High Elf relations. The Silver Covenant was born in Wrath to oppose the Sunreavers, continuing to show that High Elf vs Blood Elf animosity.
They briefly acted together in Cataclysm because Halduron was desperate for help.
https://wow.gamepedia.com/Zul%27Aman
You can still see the spite between High Elves and Blood Elves here in the brief team-up. Then in MoP of course all hell breaks loose between the High Elves and Blood Elves in the Purge of Dalaran.
In Legion the High Elves assisted with the Nightfallen Rebellion, yet again still it's shown there was animosity between the High Elves and Blood Elves (and heck even the Night Elves vs Blood Elves).
https://wow.gamepedia.com/Nightfallen_rebellion
Btw look at that, "historical,
racial, and cultural differences."
And now in BFA we have as before the High Elves among Alliance troops and citizenry, especially within the 7th Legion (these High Elves are also factioned with the Silver Covenant too btw).
https://wow.gamepedia.com/7th_Legion_Battle_Mage
TL;DR: The majority of those that want to High Elves to become playable want to play these Alliance Elves that have consistently been shown to work with the Alliance and loyal to their causes and have had different story progression than the Blood Elves.
Most of the High Elf fans don't want to play Blood Elves or twice-traitorous Blood Elves (Void Elves). This is the biggest showing of cognitive dissonance Blizzard has had on the topic of High Elves.