We have been complaining about the lack of exposure mode setting with U1/U2 for two years, since the D7K came out. It is the one piece of the puzzle that forces you to adapt to the camera, and therefore it took me at least 6 months to adapt to the D7000. And yes absolutely if I could reutilize P, S, and Scene modes I would end up with U3 - U5 which would be fantastic.
On the plus side, U1/U2 allows one to memorize a default exposure compensation and many other settings so I ended up preferring U1/U2 to Custom/Settings banks.
One final thing, I found it helpful thinking of PASM as a single U3 mode as they share all the remaining settings on the camera.