I'm not concerned about it being used against me. Like most people, I'm not going around committing crimes on a daily basis or trying to hide nuclear launch codes. I just like to have a right to some privacy in my daily life, and I don't think every detail needs to be logged and available to the world.
How about all those bizarre or misapplied laws you could be violating if just someone knew you had done it. With pervasive monitoring, the uncommon-but-horrifying could become more commonplace:
http://kottke.org/13/06/you-commit-three-felonies-a-day
What you do can be construed as criminal if the prosecutor is interested enough.
