Basically, too many things key off of movement.

Two key examples...
1) You've just hit me with Flurry, but you rolled doubles. "Ha-ha...no second attack against this guy." You say "That's ok, I'll just hit this other guy." "Nope, knock back is movement, so I'm going to Carry him with me." (Yes, I know you need to have been given an action. It's just an example...and one that people would try because they forget about that whole action thing and simply remember the moving.)

2) "Hey, I've just been hit in the face by the Hulk hard enough that I'm flying backwards. Oh, what's this? A dumpster? I'll just grab that on my way."

Except both of those require the character be given an action to move. Would people forget or miss the distinction? Sure, just like they currently argue break away is required when being carried or targeted with TK. But that's players playing it wrong, not a problem with the rule.

Like I said, those were just two examples.

Another big one is moving past an enemy.
Another would be any effect that triggers after a figure moves.
Another would be Hypertime.


It is far easier to say KB is not movement than it is to say "except if the character is moving due to knock back" every time.

I can see where there are some potential problems with effects that trigger when a character moves. The other things would be changes, but not (IMO) significant. But that's philosophical debate: mostly if the ruling is going to be "this is not movement" I'd like the rule book not to say "this is movement". that's reasonable, right?