Thanks for sharing your insight and experience.
Arthur was, believe it or not, not an unreasonable man. I certainly did have a lot of fun jabbing at each other with some topics such as running shoes. I heard that at one time Arthur and Bill Bowerman started going at each other on running shoes (curved last vs. straight last) at one clinic. I would pay lots of money to listen to what they were saying then!
Quite often he simplified things too far in a public setting. He would say something like “the shoe has to be a banana-shape” or “you don’t pronate or supinate; the shoe does.” But, honestly, his knowledge and experience went much deeper than that. To summarize it in a better way, and add my own personal experience and observation; to me, there are basically three causes for pronation/supination: (1) mechanical, (2) structural and (3) shoe induced. Arthur was never keen on orthotics but I personally feel in some cases (1 & 2) you may actually need some device to correct certain foot movements. But I feel we both agree that a big part of running-related injuries can also be caused by ill-fitted shoes.
I think there is a certain element of “chicken or egg” situation in research. For example, two things that you mentioned on shoes—pronation and masses; and landing shock—I wonder how much is actually “what it is” and how much of it is “what could be”. Arthur always said that, “if you have a weak spot, you need to strengthen it; not to support it.” Again, I guess it’s a bit radical statement and some people actually might need some level of support. But that aside, I wonder if the subject, even if he/she is one of the “masses”, strengthens the foot by barefoot running or whatever, would the degree of pronation/supination subsides? And as for landing shock, if one has learnt to adjust his/her running form to landing more softly (it was Jack Foster who said we should learn to alleviate landing shock with our running form), could that individual then afford to wear more “economical shoes”?