I play left handed (left hand on the mouse) and so I use my right hand on the right side of the keyboard for everything. I have to essentially change every key binding but one and that means when I remap something to the right side, inevitably I then have to hunt down the conflict key somewhere else. Sometimes ArmA doesn't notify you that there even is a conflict.
By simply deleting all key bindings, you remove all conflicts and allow us to set our own configurations.