Well think of the Worgen / Goblin as an extra paid feature --- since you'll need to purchase Cata in order to play the new races. That's why, if they did what you are suggesting (just enable Worgen and Goblin with Shattering) not only does that take away a hugh "excitement" incentive for most to look forward to getting Cata...but you are also asking them to give you a major feature of the latest expansion for no added cost.
---------- Post added 2010-11-22 at 03:20 PM ----------
Why doesn't it make sense? Worgen and Goblins existed since Vanilla in the game.....
It doesn't matter anyway....like or hate it the fact remains --- you'll just have to wait until Cata.