Becoming truly "engaged"

I've mentioned before the rather disquieting tendency for many I've observed to not carry a technique to it's conclusion, either by resulting in a throw or an arm bar, but I've also noticed a tendency to take a technique just shy of efficacy.

By that I mean, we take uke to the point where his range of motion ends and then stop, rather than take him an inch or so beyond what's comfortable for him. This time, I noticed it with ude gaeshi, the seventh technique of randori no kata.

It's a matter of mere inches. When tori "goes through the motions", the get uke's arm coiled up but their arms are lax, loose, devoid of real purpose. Uke's arm, consequently, is bent but his hand doesn't get very far behind his own head (if at all). He not only still has his posture, he still has sufficient bicep strength to curl down and push tori's elbow away with his free hand while turning and escape.

All it took was taking the slack out of tori's arms, to engage the left hand (if we're doing this on uke's right side) into an unbendable arm. It doesn't make tori's arms "strong" as if he's using muscle, but now he has "intent" (I can't think of any better word to describe it). His mind and his body are "engaged". Some might even explain it as ki flowing through your arms.

Most importantly, uke's hand slipped past his head and shoulder line, and magically, he came up on his toes and his spine bent. Now, he had no curling strength whatsoever.

Is that "laxness" due to laziness? Inexperience (even from a shodan)? Did I suffer from the same malady at shodan or even above?

Certainly, I think time (a lot of it) breeds confidence, and confidence can often be the final, determining factor. I felt very uncomfortable and unsure of gedan ate for the longest time. At some point, suddenly, I felt okay with it. But now I see that same sort of nervousness in others.

It's amazing how you can study the basic kata for so long, and still find ways to improve.