Backtracking a little regarding barefoot running, etc., I agree that, though we may intuitively assume that cushioning in athletic shoes is important, there is not much evidence in the literature that it has an impact on injury prevention.
While cushioning does play a role, having more cushioning is not necessarily better. In fact, the softer the midsole, the more impact is translated through the lower extremity.
Individual athletes probably have an ideal amount of cushioning based on weight, training, foot type, lower extremity biomechanics (haven't even touched on that here), history of injury, etc. And, of course, surface. Weather may also affect surface hardness; runners may need firmer shoes in warmer weather and softer shoes in colder weather.
Dr Benno Nigg's 'muscle tuning model' may help explain the role of cushioning and comfort: the body attempts to minimize the uncomfortable soft tissue vibrations due to impact forces based on the individual, the shoe and the surface.
Runners depend on shoes to prevent strain to soft tissue structures including tendons and ligaments. Though there is that 'Wow' factor of putting on new running shoes that feel soft and bouncy (which may often lead to inappropriate purchases), most runners choose shoes that provide support and stability. Though the perception of comfort is important, for athletes with a history of injuries a particular shoe's motion controlling/stability features are more important.
I personally would love to run barefoot across the plains, but as there's only asphalt and the treadmill in my neck of the woods, my 53 year old structure trembles at the thought. Perhaps, as George suggests, starting from scratch...
On a related note, one recent study concluded (there's that loaded word as pointed out by Dr Phil) that new low and medium cost shoes demonstrated the same or better cushioning as more expensive shoes during walking and running trials using a treadmill. However, the rapid deterioration of cushioning several months 'down the road', which is seen in cheaper shoes, was not addressed. Nor was stability