Super Bowl Commercial Previews?

As you probably know, over the last at least 2 years, some of the Super Bowl commercials have "leaked" early. My question is, "why?" 

I don't want to see them early and why would the NFL or advertisers want them to be seen early? 

Maybe I'm just old fashioned but I want to start seeing new commercials right before the National Anthem. 

I'm just hoping for some good funny ones and a couple of of serious ones. Dodge killed it with "God Made A Farmer" a couple of years ago. 

Again, really just my random thoughts.