You cannot impact or change all of the people all of the time.
The goal is not to attempt the impossible. The goal is to persuade any people who are on the fence to get off the fence and on your side, rally the base, demoralize the opposition, and throw your opponent off balance. This ad does all of those things.
Romney hates being pranked. This is like the 3rd prank in less than 3 weeks. Romney's head will be exploding soon.