Some more hypotheses and some ramblings…
(1) People are scared. The Right, in particular, have been great at using Fear as a tool — though the Left wield it, too, as do the media to keep eyeballs glued (think local TV news). [see Glassner, Culture of Fear and Schneier, Beyond Fear]
(2) Informal and formal institutions that have shorn up social solidarity have weakened, so people don’t feel as connected or responsible for each other [see Putnam, Bowling Alone] Organized religion is one of the few bastions left, and the Right has done a better job of using it for their ends.
(3) People feel powerless to change things. Fear plays in to this: “if we do stop the war, does that mean the terrorists will strike here?” As does the lack of social solidarity (“I can’t do it on my own and who could I convince to help?”).
Taking the streets can be a great publicity stunt (it’s helped influence the immigration debate, e.g.) but there isn’t much power to be taken there. If you storm the ramparts you’ll be shot (or at least arrested and spend a lot of time and money in court) — and good luck finding the ramparts in the first place. Power isn’t ensconced in the physical world nearly so much as it used to be, and where controlling physical space really matters to the powerful, security is tight (see: miltary bases, “undisclosed location,” gated communities).
The current administration has been pretty immune to waving signs. There were more protesters than supporters at the inaugaration of Bush, and that was back when he had around half the country behind him. Waving signs isn’t going to move them. Who do we need to move?
I think the most instructive period to look at is the antiwar movement in the 60s, since it was largely a reactive movement and because it primarily addressed decisions and decisionmakers in Washington. Like you point out, the movement didn’t really garner much attention until the draft and resistance to it.
The Civil Rights movement was trying to speak to all Americans, not just the powerful, and change something more fundamental about our entire society.
What is being asked here though is why isn’t there a more reactive movement to what has happened and is happening… it seems that people are too scared to do anything about it (or even to realize its a problem), &/or they don’t think there’s anything that can be done that would be effective &/or it’s not personally hurting them so it’s not worth sticking their head out (especially since they’re confused with fear and unconvinced they can have an impact anyway). Anyway… Didn’t you know?
And I need to read that “Daily Show effect” article… I read the abstract and I think I disagree with their conclusions.