Honestly, that's one area where I feel that we're kind of weak in terms of political dialog. From what I've seen, the Brits have a stronger tradition of expecting politicians to field questions and having interviewers not let them dance their way out of questions.
I don't know if it's definitely a major benefit to do that, hard to quantify -- I'm also not sure that being able to come up with slick answers on the spot is always the best metric of a policy, would kind of prefer written questions and answers with time to respond, myself -- but I kind of do think that it would help in some cases.
But unless that becomes an expectation, nobody's going to willingly do that.