This used to bug me, but then I got used to it. Now I don't think it's a bad system at all. The thing is, in DD, there wasn't a time in the game when I really wanted to scroll. But in BD, I simply have to be able to see what's ahead of me, and plan things out.(Especially in my 800x600 resolution). In these cases, the shift button would be more annoying to use.
Just get used to holding down the mouse while running around. And for long distance walking, click on the minimap to walk around easier. If you ever need to recenter the screen, just hold down the mouse button for half a second second, and let go.
I have no problems with this system.
Tovi 