Koichi Tohei trained a little bit (a few months) before the war. After the war he was mainly in Tokyo and had only sporadic contact with Morihei Ueshiba. So....the answer is that he really didn't receive that much direct training, although he was talented and quite strong.
I'm not sure that "softer" is the best division to make, since Daito-ryu itself can often be softer than modern Aikido (see
Kodo Horikawa).
Basically, their goal was to create a type of training that could be popularized and done by the masses - Zumba as opposed to ballet. There's nothing wrong with that - very few people really do ballet because it involves so much work (and pain), whereas millions do Zumba every day, get fit, have fun, and get together with friends. They're just two different things.
Best,
Chris