O'sensei was able to do what he did because it was a natural reaction, he didn't think Sankajo!
Here's the real question then, do you think O' Sensei trained to become who he became by practicing Waza and then turning that "internal"?
I know a lot of people that espouse that same path even in CMA, and generally they don't get anywhere.
Even O' Sensei did a "#$t load of tanren(solo training), and I'd bet a whole california state lotto winning that that was the meat of his training. All the techniques, everything else he showed were just toys to perfect the application of the bodyskills he was developing in his body.
His technical foundation may have been daitoryu, but I'll bet the engine that drove that technical foundation and allowed him to figure out to a degree what Takeda Soukaku was doing was the solo training
And solo training is hard work...something that most people simply want to shirk...
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