But not everyone wants Viera (and judging the likes on the first post, it's a massive minority of the forum community who wants them) and I'm sure quite a few (or perhaps a lot) players playing this game aren't a fan of blatant fan service.

Don't get me wrong, I still hate the Au Ra and think SE could have done better (the concept art for Au Ra's, especially for the females, were far better than the end result). If Viera were added into the game, I am 100% certain they will look nothing like their concept art (and finalised art. Male Au Ra for reference) and instead look more similar to one/two of the current races.