Although Tinker Hatfield was the one who designed the window feature and visible Air-Sole unit, David Forland, the Director of Cushioning Innovation, was already working on improving the Air-Sole technology. Former NASA engineer Marion Frank Rudy is credited with actually creating the Air technology. It evolved because Forland found that he could add more air by rotating the bag that enclosed it; eventually giving birth to the Air Max which was able to hold more air then any of its predecessors.
Forland was able to innovate and inject more air into the Air-Sole unit to give more cushioning, and also lessen the foam in the midsole as much possible without sacrificing the sneakers durability and performance. Gradually the visible Air-Sole unit was extended and able to be extended to the forefoot of the shoe as well as the heel, and then even further to the entire sole, and then even further with the complete elimination of foam and a full-length Air-Sole unit. Quite literally, you were running and walking on air.