Viera didn't blow up as big as we all thought.

[Ultimatecalibur]

I also think the later you go in an MMOs life, the fewer and fewer people show interest in new races.

Just look at the census for WoW- belfs, humans, night elves are still the top three races by a massive margin- as in, half the playerbase or more plays them. Even compare belfs and velfs, same model different factions, velfs giving the Alliance their long sought high elf model.

Belfs are around 30%, I don't think velfs are even 3% of max levels- and each xpac comes with a level boost potion so it's not like the levelling process is a big factor anymore.

I'm pretty certain the lack of Allied Race characters in WoW is more on the fact that all of them are quest unlocks. You can't make a new Void Elf, Nightborne or Lightforged Draenei (the pretty races) without having a level 110 character, Exalted rep and a quest chain.

This would be like if you needed a level 60/level 80 character that is Bloodsworn/Allied with specific Beast Tribes to unlock Au Ra, Viera and Hrothgar.