My experiences with "strong nikyo at full speed" of "accomplished practioners" tell me that your last sentence seems to be true only in a certain paradigm of practice. Actually receiving a fast nikyo from Endo senseiwas one of the key moments that made me change my way of practice.
I'd like to experience that some day. The fastest, most powerful nikkyo moments that I have felt all felt like being hit by a bolt of lightning. When it was over, my wrist was fine, but it was pretty intense at the moment!
It sounds like Endo sensei does something quite different. I get to train with students of his from time to time -- I'll see if I can get a chance to feel it.