Re: Ukemi vs. Protecting your attacker
Yeh - I'e questioned this line myself. There are two contradictory arguments in aikido:
1. aikido is non-competitive because the techniques are too dangerous to do in a competitive manner
2. aikido can be used to restrain or throw an attacker without harm
I think anyone who says uke has to throw themselves into ukemi to avoid harm is not blending with the attack. Uke is unbalanced, and they roll rather than fall flat on their back/face. The force should be there already, with no 'throwing themselves' into a roll (although some effort will be necessary to reorientate the body to make it more comfortable).
What will happen in reality? I think it depends on nage's intention and experience. Having been thrown by Yamada sensei, I would say it was a very interesting experience. I was quite inexprienced at the time, but the throw positioned me perfectly on the floor - he rotated my body so I fell extremely comfortably.
Also, a previous instructor told me how amazed he was when he did kote-gaeshi in the street and the attacker did a fantastic turn (not really a ukemi, more of a breakfall).
My point is, if you are throwing someone well, you can throw them so they will turn and won't land too badly (also a point is made about this in 'dynamic sphere').
P.S. as regards my point - I think aikdio is dangerous if there is a competitve struggle