@Ceili,
Ceili, it's probably down to lack of attention span. Most Americans (and quite a few others round the world now, thanks to MTV etc) need something to give them a hit within a minute or so, otherwise it's "boring".
If they actually knew about the tactics and strategies regarding curling, they'd probably enjoy it more.
Their loss, I say.
I prefer a bit of craftiness and depth in sport or games, and curling supplies both when it's played well.