If you could double the active lifespan of a (sane, healthy) individual, you'd get twice the amount of work for the same amount of high-school and college man-years. It's simple economy of scale.
New ideas are usually adopted once the old people with the old ideas dies . Classic example is the theory of relativity. There were brilliant physicist of their time who went to their graves refuting Einstein's theory because they had invested too much of their time and effort in the status quo. Furthermore, acceptance of the theory of relativity would have meant their work was invalid.