I wonder the same thing...
A friend of mine is in public relations and he's been an interviewer and interviewee in high positions from school boards to religious congregations. He explained that like a political debate an interviewee should go into the interview with an agenda, for instance three things that you want to say no matter what. The idea is to be on your toes enough so that you can get your main points across within the framework of the questions asked. I guess it's a way of bending questions to your answers, doesn't seem like a bad idea as long as there's a fluidity and you don't totally divert the questions being asked.