To be honest us Americans don't really have much of a grasp on New Zealand culture. We know about Flight of the Conchords and that's about it. So forgive me if we think New Zealanders are a bit soft
I don't know why rugby hasn't taken off...it's nothing to do with socialism, your #1 sports-watching demographic (males 15-40 or so) would love it. Maybe it is the injury issue. Here football is going through a huge about of criticism because of the concussion factor that is leading to brain damage...I can't imagine what a tackle sport WITHOUT pads would draw...
I only mentioned the Samoans because whenever I see rugby on TV those are the guys who just dominate everyone. They are not just huge and able to take out anyone else on the field but they can really turn on the jets and score easily. In football it's possible to be a great player just by being really big and really strong but we have guys like Troy Polumalu who play safety which requires you to not only be able to put the hurt on somebody but also to be quick on your feet since you have to match a WR step for step...seems like the ideal rugby player to me