I had the impression that both times Edwards mentioned Kerry's name it was not a deliberate attempt to break the rules but a genuine mistake to a rule that suddenly was sprung on them by the moderator for that one question. The second time Edwards made the mistake and stopped himself, he almost seemed to be mocking the moderator by saying something like, "oh I broke the rule again".
In my opinion, it seemed more like a gimmick imposed by the moderator than a genuine attempt to have a question answered. Even when Cheney answered the question, he was clearly referring to Bush. It was more of a game of playing linguistic games with the moderator rather than playing by the rules, in my opinion.
It was a pointless rule, kind of like she was making a game out of it, i.e., "Let's see if you can answer a question without mentioning the top of the ticket. Whoever can do it will win a frisbee."
I believe you are right. It would be silly to have a debate with a rule that you can't mention your running mate. Gwin was just gimicking up the question.
I believe, however, it is equally silly to have a debate where the speakers cannot use notes or briefs. Hopefully, they aren't making every decision without any reference material. Personally, I think they should have their staffs with them, and be allowed to consult. After all, that is what Presidents do.