I think that there's a real question as to whether or not that technical ability ever comes to pass (at least in the context of the big throws that are a staple of almost every Aikido dojo) - even the direct students of Ueshiba often mentioned how scary it was to take ukemi for him, and that was in a controlled situation with people who knew how to protect themselves.
OTOH, if people take ukemi instead of being injured - doesn't that condition your body (the thrower) in the wrong way?
Bubbling from the old memory banks is a quote (paraphrased) from M. Saito to the point that when aikido is done properly there is no opportunity for ukemi. That leaves only the injury or the kind heart of the aikidoka to permit ukemi. Seems ukemi is a training tool (which requires nages permission to use) to prevent a trail of wrecked partners as opposed to an actual method or unique element of aikido.