Why can't today's candidates handle a curveball question? (see full video here)

Tonight, beginning at 7pm EST, CNN will broadcast a new kind of debate in which people send in their questions to presidential candidates as YouTube videos. Here comes the new debate, same as the old debate.

The reason that this debate structure isn't really so revolutionary is that CNN will still be picking the questions, continuing a style of "filtered" debates that make us forget what a real no-holds-barred debate is like. Media critic Jeff Jarvis parses this issue quite well:

CNN did give itself too much control and responsibility when it decided to single-handedly choose all our questions. They should have enabled us to select at least some of the questions and to rate, categorize, organize, and comment on them.... Not allowing that still indicates a lack of trust in us, the electorate. CNN shouldn’t be controlling this. They should be organizing it.

One reason CNN doesn't "trust in us, the electorate," is that we don't always vote on YouTube based on seriousness, but rather coolness. (The top-viewed debate video on the site is apparently one which asks whether Arnold Schwarzenegger is a cyborg.)

But really, what would be the harm of a rogue question getting through? If history is any indicator, it might breathe life into a tired format and give a boost to the candidate savvy enough to come up with an equallly witty response.

Remember the "boxers or briefs" question that was asked of Presidnet Bill Clinton during an MTV-sponsored town hall meeting in 1994? His gracious response to the goofy question gave his credibility and likeability ratings a boost and he went on the win a second term as president. (Things went down-hill after that, for reasons not wholely unrelated to the underwear issue).

Can't today's candidates muster Clinton's easy charm, his ability to take a curveball question and hit it right out of the park?