The problem with updated player races is that, unlike most of WoW's creature updates, it's a lot of work. A lot of different rigging and more complicated expressions are required. Right now, the new expansion is the priority. There's a ton of new creatures to animate. Including new animations for the Allied Races. Blizz doesn't think they'll have time to give Goblins and Worgen the attention they need amidst all that, and feels later in the expansion they'll have that time.
That is tragic. I know I want my Goblin updates. But it's also logical and somewhat understandable. I'm not going to get angry about it.