I know what you are saying. I think Dr. Paul is just too decent a person to go off topic a lot like some of the other candidates. When asked to respond yes/no he will give a quick answer usually yes/no. The top "tier" will take the opportunity to ramble on. They know that hogging time will seem presidential to some people even if what they say doesn't make any sense. or answer any of the questions.
I just listened to a radio interview where Ron Paul went in depth into his health care positions. The problems with this "debate" format is that all candidates are not allowed to respond to the same question. The moderator picks the question that each candidate can respond to. When some candidates get 14 question and others 6. The one that gets 6 will seem to have a limited agenda.