I think the ESPN one is the biggie. People in the US need ESPN to tell them when a sporting event is a big deal. That wall to wall coverage they'd be providing if they owned the rights would have been enough to turn the buzz all the way up.
My theory on World Cup buzz is:
1. We're still in NBA/NHL mode
2. ESPN sets the tone and they don't have the WC
3. How expensive everything is, less talking to your friends about games you're going to
I also believe it'll pick up as the tournament gets going.