Ellis,
(... or Dan... or Mike... or just about anyone else more in the know than me
)
I am unsure if the argument is (a) that you can learn aiki/ki/kokyu from learning 'good' ukemi, or (b) after you start learning those things from other training, one ought to apply it to one's ukemi as much as their technique, but ukemi is not in and of itself something that can 'train up' those esoteric body skills?