"Because the '2' in PSP2 really stands for 2 analog sticks."
Among all the improvements made to the NGP over the PSP, the 2nd analog stick has to be near the bottom of the list.
That being said, my biggest gripe about the PSP was the single analog "nub" due to the fact that a lot of the bigger titles were essentially cut down portable versions of console games but the lack of a second analog input meant they didn't play the same. The MGS games in particular felt limited.
Whether developers want to use touch screen input, accelerometer or gyroscope input, or even camera input as a user interface (all available with the NGP), the point is, that second analog stick is still there for traditional 3D camera control. Having it and not using it will always be better than not having it and having to come up with an alternate control scheme.
If nothing else, the dual analog set up apes a standard controller for games based upon their console counterparts. Every game does not have to have unnecessary pointing, tilting or shaking unless they actually add to the game design.
(mostly)
