This was weird. But seeing as how there were so many delays with Broadwell, I'm guessing they were hoping for an earlier release. And then when they saw they'd have to wait even longer, they just released what they had.
Right, damned if they do, damned if they don't. Apple basically decides what they feel to the be most important components, and release when they all fall into place. Us as users have to make a decision on what components matter to us the most, and buy when the model that corresponds with that is released.