Re: Staying soft.
An interesting question for people who practice at schools that do not delinate these levels of resistance is: what happens when you make a mistake?
I have trained people who, when I make a mistake as tori, (a) will just stand there and look at me, (b) will actively initiate a counter, (c) will continue the original attack or follow with a second strike, and (d) will back away and stop. Oh yes, and then there is (e) just fall down anyway.
I think how one defines and understands resistance in a dynamic situation has to do with which of these responses one considers most appropriate in a martial training situation.