The Application Frame is not new to CS6, it was first added in CS4.
If you are zoomed in on your image, there is an area of play to scroll around. Basically, you can scroll until your image is almost, but not entirely, off screen. If we forced scrolling to stop at the edge of the image, confusion may grow out of where your image actually ends.
If you don't want to see that blank canvas space, don't scroll so far away from your image, leave more of it on your screen.