I guess the way I meant it, was that you have no thought of 'I will do this technique, or that technique' - you yield in the sense that you do not resist the other, but your action is dictated by them. Hence you abandon an ego, or a will/desire - which is where philosophy really enters into the picture - for me, anyway.
This is based on something I read from Gozo Shioda, and how I understand it, anyway (as a 5th kyu!).

I certainly don't see yielding as a weak thing - for instance, in gyaku-hanmi tenkan, I see that (presuming uke pushes/goes towards you) as an example of somebody holding you, and in response, the philosophy is kind of 'Alright: what dose this person want to do? I'll help them' - hence you yield to their desire, and then lead them. I guess if you enter immediately, like you say, then it's yielding in a kind of 'expand/contract' type thing: your will is determined by theirs...or something.

All of this might be absolute bullshit: i'm a 5th kyu, after all, with a philosophy degree, and perhaps an over-active imagination or what have you...