Your feet are on the front line, being the first point of contact. Collapsed arches can get you in trouble and cause a lot of problems upstream (knees caving in etc).
Remember, Justin also had a post about feet a while back. Since then I have been trying to walk with my feet straight. This is harder than you would think. You have to constantly remind yourself to do it right. It almost feels like you are walking with your toes pointing inwards whan in fact they are barely straight.
Main Point: Walking / standing like a duck = Squatting above parallel
Check out more drills on Mobility 101.