In my opinion, I don't think that going barefoot would make much of a difference to ankle stability. Most of the input that the brain uses to process the information would be proprioceptive, i.e. joint position and movement sense, rather than light touch or pressure input at the skin. I don't think wearing shoes would have much of an effect on proprioceptive input. Anyway, I would think the cushioning and dampening features of shoes and socks would be important to protect athletes from overuse syndromes.

As for jumping off a wall from a sitting position, the reason why you get a jarring sensation is because your body isn't upright - rather, your feet are in front of your centre of gravity. This means you can't flex your knees too much or you'll fall over backwards - hence your knees remain relatively straight and can't absorb shock as efficiently.

Anyway, this is just my opinion. Anyone else agree or disagree?