I don't think Americans really care for endurance sports. We like our athletics to be explosive. We like the long ball, the bone-jarring tackle, or the thunderous dunk. Soccer kinda gives us that during a corner kick, but it is still much more of an endurance sport than an explosive one.

I also think there is no characteristic we value in our athletes more than toughness. You want to be revered, play in a big game with a separated shoulder. You want to be reviled, pull yourself out of a game with a cramp or a bruise. But soccer is a sport basically played by 11 punters. Feigning weakness and injury to get a call is about as unAmerican as you can get (and before anyone points out flopping in the NBA, there is a BIG difference between falling down to get a call and pretending you've been shot to get a call).