Yes! Interviews are a crucial aspect of the selection process for entry into health science courses. Most people focus on their secondary school studies, prepare for the UCAT but do not prepare for the interview.
However, knowledge of the types of questions asked, coaching on interview technique and enhanced communication skills can dramatically improve your performance. You should not go into an interview unprepared or not having an understanding of what you will be asked.
Personality tests (such as the interviews) rely on the fact that the candidates do not prepare, so interviewers actively discourage the candidates from preparing. They do this by propagating various myths such as: preparation does not help; there are some questions in the interview which are designed to detect if you try to second guess; preparation may work against you etc. Accredited testers know that such organisations go to great lengths to place fear in the candidates to ensure they do not prepare, precisely because preparation works! If it is really true that you can't prepare for interviews, universities should have no objection to interview preparation (rather than actively discouraging students from preparing). Even if there is evidence that the answers come across is rehearsed, interviewers have to give you the benefit of the doubt (assume you are smart/motivated to prepare and think about the issues).