It's important from a practical point of view. If 99.9% of people will consent to a certain government abuse, even if they do not condone it, then the government can commit that abuse and deal offensively with the other 0.1%. If 9% of people will consent to the abuse, dealing with the other 91% offensively doesn't work. This is what civil disobedience is ultimately all about: enforcing a law that most people don't agree with is not a sustainable approach, because there are always a lot more people than law enforcers.
Civil disobedience is luckily not the only way to reverse policy decisions. The topic seems to pick up a lot of steam even without masses of people refusing to be scanned. (I was very surprised to see that Spiegel Online [1] – one of the most popular if not the most popular news website in Germany – has the planned Thanksgiving boycott as its top-story [2] at the moment. That’s irrelevant for the discussion in the US but it shows that it’s a hot topic.)
Agreed. I think organized synchronized boycotts would be much more effective than doing "civil disobedience" and/or drama queen shenanigans at the airport. Hit airlines in their wallet (and the related travel industries), and that will have a larger effect. Money talks. Large amounts of money talk loudly, especially to Congress.