It depends on if you are a heavy mouse user or a heavy keyboard user and you are using a laptop with a restricted keyboard. Personally to scroll a document I prefer the buttons page up/down home/end. Often I also use those buttons to select big parts of a file that I want to copy. E. g. Shift+Ctrl+End form me is a useful combination. On the other hand I rarely use the numeric pad for numbers, but I also feel more comfortable typing with the left hand, I guess that a lot more people heavy keyboard user would prefer the numeric pad.
Yes the mouse is changing the habits for a lot of people, but the numlock may still be useful for some.