Your question is not terribly compelling to many of those of us who have been fortunate enough to train regularly with teachers far above our own levels of experience and expertise. Saotome and Ikeda do not "feel like everyone else." Interestingly, Ikeda does not feel like Saotome. Continuing with Japanese shihan from the "Seigo Yamaguchi line", the few times I took ukemi for Endo, he did not feel like everyone else, either --- although he felt more like Ikeda then Saotome. As for the quality of these teachers' explanations of how they do what they do, I take it for granted that I will learn much more from feeling them, watching them, and attempting to emulate what I perceive, than I will from merely listening to them.
I'll comment, since I've taken a fair amount of ukemi for all three of those instructors.
In my experience, all of the three, as well as virtually all of the other direct students of the Founder that I've taken ukemi for had some amount of the quality that we're talking about. Some had a little (or very little), and some had quite a bit. Most of them had some pieces here and there, but not a comprehensive expression (IMO).
All of them had, in my opinion, difficulty in either understanding what they had received through contact with the Founder, difficulty in expressing what they had received, difficulty in teaching what they had received - or some combination of the above. Enough so that, again in my opinon, the transmission of skills and the theories and methodologies behind those skills was severly hampered.
There are likely many reasons why this happened, one major one is that the teaching methodology of the Founder was somewhat opaque - but regardless, I think that the problems occurred.
Interestingly, Stan Pranin makes much the same argument
for problems in transmission, but with slightly different conclusions.
In any case, now that we are three or four generations (or more) from the Founder, and can see the results of the transmission over a large sampling of people, that the problem exists is clear - at least to me.