Nah, its not really about that. Soccer is about skill. The best player in the world is 5'8 165 lbs.
America has 350 Million people, we should be one of the top 5-8 teams in the world. Even if Soccer is like the 5th or 6th most popular sport. We do well in things like Swimming and Track and Field.
Swimming and track and field cost money. you need a specific place to train, most cities have none, how many have hoops?