Hi Mark, all good thoughts.
But the reality is (as Mike S. says), there are all kinds of levels of these things.
My own teacher speaks of levels of protection. 2 levels is better than one, and 3 better than two...
So, by the logic of the statements above, if I position myself so that uke has a hard time striking me, that's one level. If I use the skills you are talking about (and they are greater than my partner's skills), that's another level. If I am in a position to strike as well, that's a 3rd level. And if the movement and placement covers me from multiple opponents, yet another level.
The fact is, I cannot count on my body structure being better than the other guy. It may well be...but it may not. So in my mind, a competent MAist will still cover those other bases....just in case.
Ron (let's not throw the baby out with the bathwater...)