Originally Posted by
MyWholeLifeIsThunder
I mean short answer I guess it's just that they are part of Warcraft's history, and remain to exist within the world.
As we all know, most High Elves renamed themselves Blood Elves and ended up in the Horde, but since the first happened, we have known a small fraction of them didn't, and is now in the Alliance, just as High Elves were when introduced into the game.
It's continuity, and appreciation of it. High Elves exist still, and although now we see them also incarnated as BE and VE, that High Elf "flavor" still exists; the conversation would be much different if High Elves had become extinct and not formed groups like the SC, the Highvale, or being a large population of Dalaran.
Pretty much every humanoid race in WoW has people that want them to be playable, and in the case of High Elves, they are the oldest race introduced in WoW that is not Playable recognizable as the group they were introduced as -mainly, Alliance aligned-
Because yeah, the same Elves are technically playable as Blood Elves, but as self evident, that's not the faction they were introduced in; Indeed, "High Elves" has been the only race that has "split" since their introduction, so by any meaningful measure, they aren't fully playable, and won't be until alliance aligned High Elves are made playable in a meaningful way that recognizes that throughline as original members of the Alliance that we still see currently through Alleria, her troops in Outland, the Highvale, and all those scattered High Elves in alliance settlements. The Silver Covenant itself is a continuation of that sentiment, created during WoW, representing those Dalarani Elves against the Sunreaver and Horde influence in their now neutral city.
Note that, it doesn't have to be as their own race, mind you, but something that addresses that history -which is why Void Elves as they are don't fulfill that niche- Maybe all it would take is for some High Elves to officially join the Void Elves, we cannot deny that the most iconic High Elf is a Void Elf now, so it's a viable path forward for thalassians as a people.