Clarification: NumLock is autosprint. Meaning, you start to constantly run in the same direction. No turning, no stopping, no passing Go, until you press another directional button (camera panning doesn't count) or hit NumLock again.
I fail to see how this is useful enough to generate such an intense response. I guess for a few people, whatever. There's no harm in remapping it to something else, it isn't a function required by the game in any fashion.