They pretty much guaranteed market dominance. Maybe they want these devices sent out to as many people as possible to protect the network sooner from the possibility of interference. With all the venture capital they have received they will want to protect their investment and that means protecting bitcoin.
They would still achieve market dominance if they priced all of those products at 10 times what they announced, and they would make much more money. Regardless of whatever altruistic motives BFL may have, it is and will remain a business.
Protecting the network is a valid goal, but pricing them this low is actually extremely dangerous for the network in the short run. If these predictions and prices are correct, someone could 51% the network with less than half a million USD invested into BFL ASICs. Sure, once they produced and sent out many, difficulty would jump, but initially, someone could purchase a large portion of the first batch and pose a serious threat to the network and consequentially BFL's business.
Again, I simply cannot see why this move makes sense for them...