I am an American, and I watch Rugby whenever it's on. Whether it's the World Cup Rugby championships or the NCAA, I try to watch. However, I can see why many Americans who grew up watching football wouldn't really care for it. In football, you watch the same team for 3+ hours. I know that the full 15 player version plays for 80 minutes, but if Rugby is on in the US, it's going to be Rugby Sevens, guaranteed. Those matches are significantly shorter. 7 minute halves (10 for finals)? That's it? An entire Rugby match takes the same length of game clock as one quarter in football. It's exciting to watch, but in such a short amount of time, it's harder to become emotionally invested. You just get into it, and then it's over, bring on two more teams.
I do have to take issue with both points TWJC brought up.
1. First, as someone who is a born and raised Michigander, try saying that America doesn't like hockey in Detroit. It's not as popular as football, (nothing is) but to say it's unpopular is flat out ignorant. Popular is a relative term. Hockey has it's markets. The Big House (Michigan Stadium, capacity 113,000) will be completely sold out next January for what will be the most attended game of hockey ever between the Wings and Leafs. Hockey may not own the entire nation's attention, but where hockey is big, hockey is BIG.
2. American football was here first? Are you mental? American football is a derivation of RUGBY. Rugby was here first. It was brought over by the British colonists, and they were playing rugby on college campuses competitively long before football. American football is the mutated offspring of Rugby. Football became king, but it was most certainly not here first.
Don't get me wrong...I am a fan of football, first and foremost. I am not one of those jerky Americans trying to be snobby by looking down on American sports to glorify whatever sports are popular in Europe. If I could only watch one sport for the rest of my life, forsaking all others, I would choose football. I absolutely love the sport. But, I have to give Rugby the credit it's due. It was here first.