The way this is presented, I don't think anybody would argue with you. Of course, if we're presented wiht only two choices (duty or treason), then no one will ever say treason.
However, I certainly wouldn't say it's duty either. The government is set up so that it checks and balances itself, and, most of the time, the only need for the general populace to voice their opinion is when they vote. This is not to say that vocal criticism of the government is never needed, just that it's more of a last resort than a daily requirement.
Let me go back a bit: my personal opinion, is that the amount of political cynicism displayed by young americans is due, in large part (not totally, of course--there are lots of causes) to "info-tainment." Most people today get their opinion of the government from political commentators, rather than through actually looking at facts and making their own analyses. I don't remember the exact stats, but a study last year showed that something like 25% of people under 30 got their news by watching The Daily Show.
I'm all for criticism of the government, if the people criticizing it are intelligent, and have a good knowledge of the facts. However, if a person's "knowledge" comes mostly from listening to political opinion columnists and partisan propaganda, I DO believe their vocal criticism is doing a disservice to the country. It's really no more than spreading misleading/false information.