I think I'm a bit older than publius, but I know what he is talking about, so I posted this in his comments box:
I was born in 1970, so I know exactly what you mean about the feeling of belatedness. I remember the first Gulf War --after a few years of tiny demonstrations of Trotskyists and anarchists on every conceivable subject, we had thousands. And then it all dried up again a few weeks later when it was obvious that US military victory would be pretty easy.
We had a decade of stupid identity politics, and then in 1999, Seattle and the whole traveling anti-globalization stuff. By then, I had enough. I didn't sympathize with the cause, which seemed to be a generalized objection to international trade and governance per se, and I realized I didn't *want* to see another wave of leftist protestors.
Just like the sixties, the 1999 period was quickly followed by the triumph of right-wing ultra-nationalists who shared the hostility to international cooperation, but had the benefit of a realistic sense of how politics actually works. They took what the neoliberals had built in the 1990s and wrecked it out of a sort of Dionysian rage at the constraints of civilization.
Fighting for equality and dignity for the people who have worked and lived in your country is a real cause. Opposing another stupid war is a real cause. Good luck.
Of course, then we get into a big Usenetty thing about libertarianism. But it was an interesting moment.