Because European soccer is boring and endless. American Football is exciting, high scoring, and has scantily clad cheerleaders.
I'll see your scantily clad cheerleaders and raise you
Two years ago the Wall Street Journal did a study that noted that the ball is actually in play in an NFL game for about 11 minutes out of the sixty.
According to the article, the average telecast devotes 56 percent more time to showing replays than game action and commercials took up one-third of the broadcast time. About 60 percent of the total air time is spent showing players in huddles, at the line of scrimmage or standing around between plays.
That said, I enjoy the NFL. But action-packed? Not so much.