Because the server was still "young", once a server gets stable and stays as is the pvp population will eventually settle for one side. There is a best racial for everything, so people will play as that.
Take the 2v2 ladder on woltk atm, every single hunter in the top 50 is a nightelf. Meld>other racials, thus every serious hunter is a nelf. Its going to be the same after the dust settles. People minmax.
And lets be real, race diversity is totally meaningless, faction imbalance is somewhat of a problem but who cares if every single alliance character is of a single race.
I dont get why people keep complaining about the racials, warmane would never change it, most people dont want it to change. Its a massive change that wouldnt really affect gameplay. One faction will always have a lot less pvpers, especially on a "small" (compared to retail) community like warmane woltk. If they were to fix stuff theres way more important and gameplay changing stuff that deserves much more attention, sacred cleansing for example.