Super Bowl Marketing

Since the Super Bowl was last Sunday i thought i would share some thoughts about the marketing that takes place during the Super Bowl. I was sitting there watching the commercials and thinking to myself about if it is worth millions of dollars for you're 30 seconds of TV time. This is one of the few times that people actually look forward to the ads. People look for the commercials to be funny and it a good break up during the game. One thing i noticed, however, is that all the products that actually had ads were very well known. Coke, Dotritos, Go Daddy, and Budwiser all had long ads during the Super Bowl but why? We all know these companies, and ad during the Super Bowl won't bring them any more customers, especially enough to cover the 3+ million dollars that it cost for the ad. So why do they do it? One of the only reasons i can think about is that they want to stop other companies from getting their commercials on. There is an advantage to having you're commercial during the Super Bowl but in order to afford it you need lots of money and only the biggest companies we all know and love have that type of money, so what is the point? Any Ideas?