How did the DMCA ever get passed? It's an absolutely insane, ludicrous set of laws. I'm going to start selling shirts that say "Today I Broke The DMCA". No matter who wears it, it's probably true.
You can now run a social network and not get sued into oblivion for users putting up copywrighted content, so long as you're not too complicit in the behaviour. Safe harbor is a win for the internet in my book.
Without safe harbor, Google would be liable for re-distributing movies that people keep on uploading to the site. Takedown requests get a bad rap, but it's not the worst possible scenario IMO.