I think Americans prefer watching sports with variety. Baseball has the thrill of the homerun, double plays, 98+ mph pitches, squeeze plays, and stolen bases. It is a boring game for the most part, but it has a number of payoffs. American Football has an unbelievable amount of payoffs (sacks, long passes, field goals). Soccer only has the occasional goal.
Most sports involve teams taking turns kicking, hitting, throwing, slapping, or hurling a ball across court. Soccer, volleyball, lacrosse, hockey, and tennis are loved by people who actually play those sports. To people who do not, they are incredibly boring to watch. I play tennis and volleyball and I can't bare to watch them on tv.
Why then is basketball popular in the US? I really don't know. I can't stand the foul-a-thon at the end of every pro game. I would guess that it is popular because you don't need a lot of equipment to play it and every school seems to have a basketball team.
I'll never understand NASCAR. I live 600meters from an interstate and I can watch cars zoom around all day and see the occasional wreck.
