i won't beat up soccer, it is fun to play...but i have zero desire to sit and watch a whole match. even when the US is playing well.
here the best athletes do not play soccer, they play football or basketball, and that detracts from the games appeal. also, the world cup taps into nationalistic zeal...our best against your best...but in the US, the best play other sports.
plus life in the US is such a fast paced, pressure filled, surgically enhanced, self absorbed whirlwind...i think the idea of watching a match for 85 minutes and having it end in a tie makes us feel like we just wasted our time
i think there is room for soccer to grow here, but i think at best it will be held in the same regard as ice hockey...loved by those who played in their youth, ignored by everyone else.