David Valadez wrote:
Why does body art NOT (or tend not to have) have this violent dynamic (occasional bonks and raps that come and go with no mention; primal instincts of self-preservation; etc.)?
I think our imagination fails us here.
Few attacks during practice are deliverd full speed, full power, full intention. (And a lot of the time rightly so, but that's a different discussion.)
If someone swings a sword at your head it is easier to convince yourself that this is a serious situation. If someone grabs your wrist (the other side of the spectrum) and pushes, it is hard to get the same feeling, although a wrist grab doesn't need to be all that harmless. (Perhaps a better example: morote-dori can be used to go to yonkyo.)
So the problem might be that few ukes attack properly, often they lack the skill and the proper mind-set. You can observe this as well in uke's attack, as when tori/nage has begun doing a technique: many uke seem to think that all they need to do after attcking is fall over at the right time. While what they should be trying to do is moving in such a way as to try to gain advantage. Many techniques make little sense without uke trying to do so.
Gaining the skill should be quite easy, it can be thaught. Training the proper mind-set tends to be quite difficult, at least that's my experience.