I hope you don't go to Starbucks and complain about the songs they give you for free.
It has been a long known fact that developers and companies will try and get out of these promotions as much as they can. That is why the App of the Week is frequently just Angry Birds something.
I don't know if Apple gives developers a flat payment for when they do these things, but Amazon doesn't, and even when it's offered, a lot of developers don't take it because it still loses them too much revenue. And in return, they get a bigger user base they can't deal with because of it.