I wasn't thinking of anyone using the X-Key (other extra 'keyboard') device for movement necessarily. And I should have probably clarified that I'm referencing movement control in relation to the main character controlled.

I was musing as to if people like yourself might solely use the mouse for movement instead of the keyboard. Since in WoW if you hold down both mouse buttons you run forward.

Which isn't something I'm used to doing, but makes sense in using something like the X-Keys wouldn't really be an issue since the left hand no longer controls movement.