I posted a longer comment about this last night[1], but the short version is: Amazon is clearly much more interested in profiting from content than hardware. That means they want cheap devices that people will take everywhere and read lots of books on. The Kindle DX is less portable (and thus you're less likely to take it on your commute, etc), and its main advantage is for reading PDF's, on which they make money.
So I think it will be an expensive second-class citizen for the forseeable future. It's not in their interest to change that.