Except the game has been out for a long time, and a PSP version is coming soon. Trying to make people visualize what the touch screen could have been used for. Metal Slug 7 on the DS uses very minimal touch, and I feel it was more of an after thought when they made the game. I also feel it would have been far more easier to switch your special weapons with the touch screen, and have the R button only for the pistol.
Just trying to make the game less complex. The idea of the first game was fantastic because you only needed a joystick to move and three action buttons.