a)Blizzard doesn't have the full extent of private server data, so making the decision off of data that they did not compile is unlikely
b)Private server data can be skewed by a few different variables, including playerbase and knowledge (a lot of people who play Classic don't research at all, and just play the game).
c)Players will drive their own faction balance. Some people refuse to play on horde, and that's okay. Some people love Blood Elves, and that's okay. Don't change either.