After discussions with Matt and Brecht, I took their advice and just rolled the functionality into the “UV Project from View” operation. So, if you’re in a camera view and use Project from View now for your UV coordinates, it actually works like you’d expect. Before, this resulted in a nasty mapping that had to be scaled, skewed and tweaked by hand to even get close to working. Now it works as is.
The whole point is that if you want to do some quick camera mapping for 2.5D matte work and don’t want to deal with the UV Project modifier, you can just blast it to UVs from camera view now. The nice part is that you don’t have to do anything special to use it — just jump into edit mode, press the U-key for the Unwrap menu and choose “Project from View.” If you’re in a camera view, it’ll do it.