I found it understandable because McCain was throwing out straw-man after straw-man, which is worthy of interruption in my book.
Personal attacks, In the way we deal with them on this BBS, are by nature handled differently in a live debate. We deal with them on a paragraph at a time basis, With time to think about our responses, and being able to say (or type) something without interruption. A live debate is what you have in your head, right then and there. You don't have the time for carefully measured responses, Unless you are simply reading scripted lines' off a peice of paper. You have to reply to questions hitherto unknown, Attacks or otherwise. Obama's interupting of McCain is a good example. It proves to me that Obama isn't tied to a telepromter; And by the lack of some of McCain's sudden jump-up-and-say-it lines, He might be in a situation that would go from calm, level-headed reasoning to blaring profanity in seconds...Which I'm sure that McCain's staff wanted him to avoid. If he went into that debate acting the way he sometimes' does on the Senate floor, he would have been in real trouble. It looked to me like that was the one thing he was trying to avoid at all costs.