I take the view that having a good ukemi is vital and useful to be able to do. I also think that it is not always the case that you have to use ukemi in training.i think knowing both methods is good .DH makes the point that you can feel your partners power or lack of without doing a ukemi. Until very recently I used to take ukemi, I have cut back on this and rarely do I breakfall. This does not stop me from feeling my partners kokyu./kuzushi. If you take someone with a bad back and throw the person around I do not think the back problem will improve.On the other hand stretching and assisting your partner in a controlled manner can in some cases prove beneficial.I try and utilise ukemi more than falling ,more like body conditioning .My view is both D,H. and the other contributors viewpoints have merit.
I agree with that statement though. That you can feel kuzushi and cause It without having to complete a full ukemi. On the other hand some moves just completely takes you off your legs that there is no other option but to take ukemi to save yourself. The only other option is to hang on for dear life and resist which is far worst for the body to my mind.
Still I can see merits of not having to throw your body around. The only possible negative might be nage won't have any practice of following through his techniques and that might cause problems later.
And I guess you won't Parkourists in their 60s anytime soon. You need a certain amount of daredevil and couldn't care less attitude to do what they do, and a healing ability close to teens to get back up after fails. And yes, there are plenty of fails for every successful video you see out there. In fact that's why there's kind of a split in ideology for the founders of Parkour and modern practitioners. They just wanted a way to move smoothly and effortlessly across an urban terrain...
As a way to get back to topic, perhaps that's why so many of us remain clueless on how to do Aikido. Because we still don't get what Osensei was thinking when he started it. Maybe a fresh and different outlook could open our eyes a bit... Thrivemovement.com