Americans don't like soccer because we like points, and soccer has no points. The rules allow for the scoring of points, but it rarely occurs, and when it does, it's a fleeting moment created seemingly by chance. The game instead consists of a continuous back-and-forth of the soccer ball over a vast field, punctuated occasionally by fouls, players pretending to be fouled, or the ball going out of bounds. When a goal does occur, if you're reaching into the popcorn bowl at that moment, you have nearly no warning and you miss it.
As Americans, we simply can't concentrate that long. We need satisfaction. We need something we can hold onto. We need points. Even in an American football game, which to me is boring as dirt because it stops and starts every three seconds, the ball gains or loses yardage, which feels like points. Also, that it starts and stops every three seconds means that we only need to concentrate for a few seconds at a time. Baseball is the same - the action only occurs for a few seconds at a time, and players advance around the bases, which gets you measurably closer to winning a point. This is the opposite of a soccer game, which is one continuous blur of running and kicking, signifying nothing.