As someone who does a lot of walking, I have more than a casual interest in comfortable footwear. And I always assumed that the sneaker, independent of whatever bells and whistles come out each year, has been largely perfected as a product: A hard outsole on the bottom and a soft, cushy midsole against your foot, wrapped around the top with a fabric upper and some laces.
Sneaker designer and Go-Lite Footwear owner Doug Clark, who has thirty years of experience in the field, knows better. The central design of sneakers, he points out, is flawed; they've got the bottoms on upside-down. For example, let's say the wearer steps on a small rock or irregularity protruding off of the ground. The rigid outsole will then act like a lever, see-sawing your foot into a skewed angle and, if you're elderly or have a poor sense of balance, lead to possible injury.
This is one of those things that takes several sentences to describe but can be understood visually right away. If you're not a footwear designer, you may not be willing to sit through the following video's amateurish presentation and god-awful camera shake--did they film this in the back of a helicopter?--but if you want to see the central point, fast-forward to the 2:00 mark.
If you want to read more about Clark and his methodologies, there's an in-depth local-paper article on him here.