Personal Identity Should We Shield It?

I've explored numerous blogs, and many shield the identity of the blogger. I've got it all out there. Jen Carbonneau that's me. What's my worry? Should I become a Mrs. C or another pseudonym?

All I can think of is the Ender's Game series by Orson Scott Card. Two of the characters, Valentine and Peter Wiggin, use various names to establish online identities. Eventually, their true identities are revealed and they end up in powerful places.

My questions to all of you: Why do people hide themselves from the online community that they influence? Do you? Should I? (I know that it's a personal choice on my part; I just want to explore possibilities.)