Re: Kotegaeshi, help please
I pretty much agree with all of this.
My pushback on the idea of static technique is because, except at very high levels, static situations make it very easy for uke (consciously or unconciously) to subvert the goal of the training. Uke doesn't try to control the center, they just stand there. Or they adjust every time nage starts to get them moving. Or any of a number of things.
For advanced students, sure, that's part of the training. But pedagogically, static technique is often used to walk beginners through the "shape" of "foot goes here, hand goes here." Without careful explanation of what's going on, it very easily becomes a strength contest that beginners simply don't have the tools to win. So neither uke nor nage learns anything helpful. IMO, correct ukemi for static technique is even more difficult than good ukemi generally. It's easier for uke to "win" in a static situation, and it's hard for people to remember that "winning" isn't really the goal.
"Kuzushi on contact" is great, but that isn't what you're training if you stand there and wait to engage until uke grabs you. Rather, you're training how to recover from your failure to achieve kuzushi. Which is a useful skill, but doesn't teach much about timing, connecting before the moment of contact, and other skills that are essential in a dynamic encounter. In my experience, people who do a lot of static training are often not prepared to handle a dynamic situation: they're used to being able to take their time and "feel out" how to move uke.
Of course, people who do a lot of very dynamic training can find themselves unprepared to handle it if uke does actually manage to establish a solid grab. Any training method can be overused.