Well for a long time when the series for started, USA dominated. This Cup was the largest attended event live in it's history, so I doubt it's going anywhere. It might need some tweaking such as expanding the field of players to include Canada.
I think when US kicked butt, the European side took it as a fun break from their usual tournaments and did not really care if they won or not. I've seen some of the early videos and the European guys are drinking and smoking, joking around, and the US is all "whoooot, we are winning!"
And the rest of the world had no idea how to play US pool games even if they could pocket balls, watching some of the early Chinese and Japanese entries in US tournaments, especially the women, was pretty sad, they'd miss like 2-3 times a rack, be out of position the same amount.