See, my point of view is that it's a Damocles' sword on both parties, this privacy play.

On the one hand, by giving information about you and letting Google process it, you've seen the results - Google knows what you want before you ask (or even knew) you wanted it. It is a great assistance to us, and useful in so many ways.

On the other hand, information IS power. Less scrupulous companies could do any things with that information, from annoying to shady to downright illegal. For instance, they could blackmail you or get you fired if you don't do XYZ, theoretically. Or a government could (I think I should say has at this point) forced Google and others to hand over data about people, which means that should they decide that they disagree with what you have to say, you couldn't escape it.

So the long of the short of it is, in my opinion, that today we have the power to harness information and use it POWERFULLY - both for good and for bad - just like the discovery of nuclear science gave us nuclear reactor and medicine... and the atomic bomb.