I'm pretty sure if Subaru could churn out a ton more Imprezas, they'd be doing it. But you have to remember they are a small carmaker in the big scheme of things, and you don't just bring additional production on line like that. Unfortunately, it would appear that the smarter course of action right now is to NOT order your car, but find one in transit, then plug-and-play with the add-ons that would normally get installed at the port anyways. I doubt they realized how big of a hit the redesigned '12 was going to be. And as for the dealers taking orders that they won't be able to fill easily, that's business. I've seen a lot worse sleaze in the car biz than that, be thankful that they're not giving you more of a runaround and trying to hang onto your deposit to keep your business at their dealership.
Do some homework, check a lot of dealers, and see what you can find. You might not get exactly what you want, but with demand so high, beggars can't be too choosy.