What if one of your Facebook friend's accounts get hacked and the hacker can access a ton of information about you? What if a friend's email gets hacked? What if your phone is stolen?
There are far too many different scenarios that essentially lead to the same result as the event you mentioned. I must repeat myself again: ignorance is bliss.
Also, to answer your question, I really wouldn't care because there is nothing I am trying to hide from anyone. Some documents, programs, whatever. Not like I'm part of a top secret organization.
Oh and BTW, the hardware usage data from DiRT 3 comes from those who opted in on Steam.