I admit that my sensei can be intimidating, especially to new students. He is getting older though, and I hear that he is getting softer in his old(er) age.
That said, I've only taken two ranking tests, but found that even though I was not nervous before the tests when I stepped on the mat it was a different ballgame. Performing under pressure and overcoming the adrenal response brought on by that pressure IMHO is one of the beneficial aspects of the testing experience. In my limited experience, I hypothesize that frequent randori practice coupled with the pressure of testing situations (or even taigi in ki society)is a good start to overcoming the "freeze up" that is a natural response to the onset of fear, and intimidation on the part of instructors/sempai is completely unneeded.