Every generation has said something exactly like this about the generation before (modern, postwar, postmodern, etc). However, I agree that we are in an age where most (if not all) big fuzzy ideas have already been thought of. People have already suggested that "God is Dead" (or nonexistent) or "God is all knowing and all powerful", and everything in between (even that a flying spaghetti monster controls all). Nobody is going to come up with something more radical on that spectrum. Its now on to morality and efficacy. Morally, there are still active debates on topics such as gay marriage, abortion, scope of the government, and cloning. Everything else is about efficacy, and what actually works. Big ideas are the easy part. Proving they work requires intellectual vigor, experimentation, data, and analysis over long periods of time. If big ideas are dead, then its only because we are on to the good stuff, figuring out if they were worth anything.