I actually had this conversation with a coworker yesterday.
If you look at it rationally, the justification explains itself. Your foot contains 25% of the bones in your body, supports your entire frame and is what essentially allows you to move.
If you do not properly support it, and that includes wearing shoes that are the proper width, proper length, and the proper shape, the following occur: foot problems, back problems, and knee problems.
This of course...