The "soft" or cotton-end of the tension range is, in my personal experience and training, more useful with identifying an internal connection or path and following/sensing where it goes inside my body.
It's my understanding (and I mean that in mostly the intellectual sense) that that
is the key. That
internal path/connection is what is then strengthened, creating the "steel" aspect, isn't it? The jin/kokyu is the backbone of the "strength," which is discovered and felt through a relaxed (soft?) body. Then, there is the development of the supporting "structure" once the "path" can be found and manipulated. Isn't much of the connection/jin/kokyu a learned skill? The re-wiring, as it were? In learning any new coordinated skill, I would think a relaxed "soft" approach tends toward picking that skill up quicker. During the process, some of the key aspects of "structure" are unavoidably strengthened and identified, to then be further conditioned. Perhaps this next round of conditioning is what some are referring to as "soft" and "hard"?
I am a bit confused, however, in how what gets classified as "hard" and "soft". I think most of the time we're entering into something shoe-horned into a classification that doesn't really fit into what's going on. Not to mention the distinction between training and application.
I'll sit back now and hope the rest of you can clear up my confusion.
P.S. Sorry about my lavish use of quotes, but I'm trying to use the common phrases bandied about, without committing to them, until I know more.