Don't forget that Blood Elves seem to have lost the initial edge they were sold with anyway;what with the restoration of the Sunwell. Given they feed on a font of holy and arcane power, the High Elves are irrelevant as traditional elves. The Blood Elves ARE the traditional elves now. It's a good niche. Someone has to do it. And it is interesting that in this universe, it is the Orc allies who fill that role.
Given the Void Elves are shadow based and alliance aligned, they are perfect foils for the Blood Elves going for.
The High Elves are utterly irrelevant in every single conceivable context.