The WJHC is always bittersweet, especially for Canadians. Rarely is it a contest of the greatest junior age players, but rather a contest of the greatest junior age players who are too young, or not quite good enough to be on their NHL squads. And I think Canada suffers for this more than most countries; European/Russian players aren't usually rushed as fast to the NHL due to language/cultural issues, and US players tend to stay a bit longer in college than Canadians in the CHL (or so has been my casual observation - I'm sure I'll be harshly corrected if I'm wrong).
For the question at hand, I agree that the US squad looks excellent on paper. However, as the 2004 Canadian junior team will attest, the best team isn't always just the team with the best players.