I understand what you're saying, Rupert, and maybe a little of that is happening too.
All the same, I know what I feel, and nikyo delivered by someone who does it the way we are talking about does feel very different from nikyo done by someone who is not controlling uke's body structure.
We were practising this very technique yesterday evening (funnily enough), and I was experimenting with which part of use's body I was controlling through the wrist. If you aim your technique at the wrist, or try to control the front shoulder, this relies on uke feeling pain in their wrist for effect, and you have little control on their body apart from this (especially if they have insensitive wrists). On the other hand, if I try to link the wrist pin with uke's rear shoulder, they go down with much less effort on my part, and they tell me they feel much less pain in their wrist.
I know what you're saying too, and it makes for good technique. But I remain a realist and for me, that good technique offers a faster route to pain, should you chose to take it. The more choices you have the better.