You wrote:
I never said that small increments don't work....
And you wrote:
No way possible that a change from 170 to 175 cranks will produce the dramatic changes in positioning, pedal feel or anything else!
IMO, you certainly imply that's a small change that will have no effect. At least that's how I read your post.
It was awful in the 70's....
Yeah, bicycling was limited to just a few hardy souls in the '70s....
I always chose my gearing based on the terrain I ride, although I did ride RI hills in the '80s with my Chicago N. suburb (flatland) gearing. My knees were fine.
I think you're referring to leverage. Yes, the shorter cranks reduce leverage, which make it harder to turn the cranks, but they also reduce the circumference of the circle the pedals need to traverse, so it may be easier to spin faster, and as Nick mentioned, they will reduce the knee angle at TDC. But whether or not changing the crank length by the OP is a right thing to do is an experimental question - although the shorter he is, the more likely it is to a good choice.