Have to disagree to some extent. If uke was allowed to change his grip in accordance to Tori's movement (this would be a stronger position for Uke because it evolves like in real life), then Uke wouldn't be able to do that technique at all. A strong position will constantly evolve. That's the basics of Aikido.
All these type of demos fall under the false pretense that Uke is going to be a static loaf. They do teach a basic principal but like you said it's blatantly obvious and totally one sided.
I would respectfully disagree with your position. The level that Dan is talking about is one in which your time frame is slower than the person with aiki/internal skills. Your body simply cannot process the information overload quick enough to be able to offer any kind of effective response. At that level, by the time you have made contact, you are already behind the eight ball, which is behind the wrecking ball that is about to hit you while you just notice the eight ball. You have to experience this first hand in order to truly grasp what I am talking about. I know personally! I have always been congenitally stupid enough to insist that I look at the eight ball while the wrecking ball crushes me far more frequently than I should have, before I had to acknowledge the inadequacy in my training and abilities so that I could be open to learn what Dan is talking about. I genuinely hope that one day, my congenital stupidity will wear off enough to actually learn this stuff well enough to be able to do it in a real-time manner.