A big reason why ( and I have heard this many times) Soccer is a difficult sport for the American people to get excited about because its not an interesting sport to bet on...the goals/points are so few and far between, many have suggested if there was a way to make a more interesting point system (like football) that people could wager on it, it would be more popular....American public likes goals goal goals and lots of points and action....
Think about it, football has all these points (24-28 a game or so per team) but that's still only 3-4 scores a game....its the point system that's more creative.