Maybe because they’re inside the Alliance for fifteen years, and Alliance players have been asking to be able to play as one since then. They’re also a perfect fit for the Allied Races system. I agree they wouldn’t work as a Core Race, but as an Allied Race they should’ve been the first pick, and last but not least, because they’re heavily requested compared to any other Allied Race suggestion.
High Elves only need minor changes to not look like carbon copies of Blood Elves, this is the only excuse for High Elves that needs to be adressed. Anything else is just acting out of spite against other people.