If you have nothing to hide
I think people who honestly believe that 'if you have nothing to hide, you have nothing to fear' have absolutely no understanding of the word privacy.
I've not done anything illegal, however, I'd very much like to have a shower without someone unknown to me watching, I'd also like to talk to my doctor about my medical conditions without anyone who doesn't need the information knowing.
Neither of these acts are criminal, but in a world where mass surveillance is normal, how long before every action we take is monitored. Privacy isn't about needing to hide illegal things, its about wanting to hide personal things.
(Or, if you have nothing to hide, thus nothing to fear, can I take a photograph of your genitalia and stick it on the internet with identifying details - also, can I listen to your private conversations with your partner about what you'd like to do to them in bed, and broadcast them on the radio? - No, why not, nothing to hide after all)
