First of all, allow my to make a bit of social commentary as someone who never really got into any team sports (probably because most of the people I knew growing up who WERE into team sports were jerks who picked on me in gym class).
A: Americans say Football = Soccer and American Football (i.e. America's idiotic bastardization of Rugby) = Football more as a matter of convenience than anything else. You say Football (meaning Soccer) in the U.S., and you automatically have to disambiguate. Nevermind if Soccer "deserves" to be called Football; in the U.S., it's never going to happen.
B: My roommate from Nigeria has a theory as to why Football (Soccer, that is. See what I mean?) was slow to catch on in the US, and that was because the low scores and the frequency of ties make it a less exciting game. My theory is that it's more a statement of America's decadence since it's difficult to gamble on a game that has a high probability (if the teams are any good) of ending in a nil-nil tie, and that it doesn't make much economic sense to promote Football since there's very little specialized equipment to be sold.
In American Football, if you want to play NFL regulation, you have to at least fabricate a pair of goalposts and set them in the ground in such a way that they won't fall over (a pretty hefty construction feat for such a large and poorly-balanced frame structure, mind you), and if you don't want your skull broken or your ribs shattered or your nutsack pummeled during play you have to buy expensive helmets, armor for every square inch of your body, spandex trousers to keep all that cumbersome padding in place, a mouth guard, and if you feel like being able to outrun or outmaneuver the competition I hope a good pair of cleats is on that shopping list of yours. Tack on gloves to keep the ball from slipping out of your hands all the time and a custom-printed uniform on to that and the overall cost is probably around $200 a player for consumer-grade kid-sized gear and up to $1000 a player for the custom-fitted adult-sized stuff.
The all-important ball is reduced to nothing more than a line-item, and when you consider that a typical American Football team (from little-league to National-league) will probably have at least one-and-a-half to double the number of players on it as they field at any given time, that's easily one to twenty-thousand dollars of sporting equipment present at every single game, and the more advanced you get, the higher your equipment costs. Any American kid hoping to play seriously for most of his youth will probably need more money put aside for equipment replacement than for his college fund.
Compare to Football, all you need is a $15-$30 USD ball. That's it. You can play in bare feet and mark out the goal lines in the dirt with some sticks if you have to. Even at the top levels, the only things you really need are cleats, shin-guards, goalie gloves, and two big nets to put on either side of the field (both of which can be properly secured to the ground in the time it takes to get just one of AmFoot's uprights upright).
As an aside, Rugby has probably about the same equipment needs as Football, which also explains why Americans don't like it more (though not as much as the fact that Rugby is AmFoot's older, smarter, more refined brother who could still kick his loud-mouthed, bratty sibling's ass every single day of the week if he wanted to).
So in other words, America is backwards from the rest of the world with respect to Football because American Football is the only sport that's stupid and wasteful enough for us to really get into and because the spartan, athletic, non-contact nature of Football doesn't appeal to the typical American slob's penchant for high production values with little actual depth and lots of physical violence.
And to remove all ambiguity, I am an American, and while I do like my country pretty well I think a lot of the people who live here and a lot of the things we do here are fucking stupid. American Football epitomizes many of these problems, from the high costs of single-purpose equipment, to the fits of unrestrained violent contact so intense they have to pause the game for three minutes after every play to let the player's brains reset, to how the winning teams always thank God for their victories while the losing teams always blame themselves.
Sorry for the tl:dr post, but I hope it's at least informative.
I prefer watching the NFL anyday, but thats just my preference. I do think interest has been steadily going up for the sport, though, and thats a good thing.
