"If you are facing a person with a sword, get used to the idea that you are going to get cut. If you can live with that, you have a chance of surviving. If getting cut is a problem for you, you're going to die."
I've thought about this a lot over the years when practicing weapons defenses. I'm by no means an expert in this area, but I believe he has a point.
Good point. If one is fearful of dying in the face of an attacker then the mind becomes confused, locked, fettered and unclear, which seriously helps decrease ones odds of survival.
Having done the exercise you quoted above, things worked quite well when I allowed the Kendoka to come at me as if he were seriously trying to kill me. When he went into the cautious, "fight mindset", "sport Kendo" mindset it was more difficult to execute waza (not impossible though) since he gave much less energy to work with, which meant I had to generate my own.
Your point is very important. Many who attempt to apply Aikido under resistance start with a "fight", contest or "struggle" mindset, which is exactly the opposite of Aikido's core tactical approach. When one sees the situation as life and death, regardless of whether faced with a weapon or not, ones entire approach to the engagement changes. It is this approach that creates fertile ground for Aikido waza to operate against real threats. There must be Mushin, else Aikido simply won't work very well, as this is a foundational element. This goes back to the thought on assumptions as well, all of these things help in clouding the mind. A good example was seen in the "Aiki-Boxing" thread where the Aikidoka started to "fight" and "struggle" (which led to more half-baked waza and Judo type moves) with the attacker as soon as he donned protective gloves. When he went empty handed the Aiki waza started to flow.
I maintain what I said earlier in this thread, the method works. The real question is, how many are willing to do what is necessary to get there? If one is "fighting" or intending to struggle with an assailant, one is not doing Aikido.