The aikido curriculum was dumbed down and made the way it is today simply because 99% of Aikido practicioners would probably drop out. My guess is he just wanted to spread Aikido as something that everyone could practice, and didnt care whether or not the "essence" got transmited. Otherwise I think you'd see much more information on the way he trained in private
I think there's another plausible explanation.
Maybe he independently achieved Sturgeon's Realization
, the unexpurgated version of which is Ninety percent of everything is crap.
If you add that to the very real risk of a skillset disappearing due to small numbers of practitioners, perhaps there was a sense that insuring a larger body of practitioners of a "lite" version of the same art would increase the size of the group comprising the 10% that isn't crap and the 1-2% that truly excels.
As we see from these discussions, there is certainly a proportionally small but vocal group of aikido practitioners who have a definite interest in something more than martial arts lite; if one looks at the ranks of those practicing DR, as well as those studying related skill sets, there are a lot of folk who found enough to attract them to MA in aikido, but who continue to press on for more.
Perhaps that is a sign things are working out exactly as hoped.