Thanks for the quote - it's very insightful - I had read about the emphasis on the big toe in Yoshinkan (but I had mistakenly taken it for the big toe in the front foot for stability.) I will have to experiment a little with this.
When I first started Yoshinkan Aikido, I thought the same thing. I was concentrating too much on the big toe of the front foot. My sensei corrected me and it made a big difference not only in my balance, but rooting with the back leg using the big toe and movement back and forth, especially in the hiriki no yosei ichi and ni.
I actually worked on the Yoshinkan kihon dosa last night and made a real conscious effort to understand what was going on inside my body (muscles being worked, balance and the use of the big toe). Just experimenting and trying to understand this stuff. I also tried one of the Aunkai Ten Chi Jin exercises just to try it out. It was tough but interesting enough to continue exploring. Self study and exploration can be challenging at times, but it can also be very rewarding.