What do you mean, imbalanced? I never had any problems with balance when playing Warcraft 2. Orc-players were just plain better than those pesky humans ;D
On-topic:
I think they don't want to rush anything on this. Players have been waiting for years on this, and they expect something very very great now, so they can better hold it off for another couple of months instead of releasing something that doesn't make you "wow" when you play it.
I don't mind all that much though, gives me more time to save up money for a new PC to play it on ;D