There was a very good article on that subject in Chronicle two years ago. (http://chronicle.com/article/Why-Privacy-Matters-Even-if/127...)

IIRC Bruce Schneier has made an excellent point too: "nothing to hide" becomes destructive the moment those in power get to decide what is the current definition of "illegal" or "dangerous". Just find all occurrences and shows of support of the $new_threat in the available personal histories and persecute at will.

In other words, it's never the right approach.