The only way three people can keep a secret is if two of them are dead.

If secrets didn't exist the world would have been a different place. We would have been left to live without the need to discover and nothing there to ensure us that our environment limits aren't exhausted.
The world needs secrets, it needs uncertainty and destabilization as much as it needs comfort and security. People feel the need of surprise, the thirst of finding what is at the other end- like a prize that lies in wait. It is as if we are children again and the ways of world are infinitely mysterious and someday we might grow to know and master them.

To me it seems that secrets only make life more complicated and misfortunate than it needs to be. Like in that story about two young people in love. The Christmas was coming and despite the fact that they were very poor to afford to buy anything, they secretly planned to find the perfect gift for eachother.
Their most valuable possessions were the boy's watch and the girl's long beautiful hair. So the boy sold his watch to buy combs for her hair, and the girl cut her hair and sold it to buy a chain for his watch.

This is a foolish story, of course and despite good reasons for keeping a secret, like being a jew in Hitler's Reich, even though the "good reasons" are dependent on bad things, they protect a life, I think secrets are only going to mess up everyone's life.