Research indicates that most programmers are introverts. There are reasons for that, for instance it is harder to get the sustained concentration that programming needs from an extrovert. You are unlikely to get displays of emotion like you are looking for from introverts, particularly not in what is already a stressful social situation (the interview).
While I agree with your advice on how to be an interviewee, my suggestion on being an interviewer is to think carefully about what you are looking for and then whether your current technique will find that. Because most interviewers wind up actually selecting for something irrelevant to what they want to be selecting for.
Note to self: my knowledge of problems that interviewers have is from scattered sources, I should locate a good book on the topic and read it...recommendations would be appreciated.