From commiting crimes? Unless you install cameras everywhere I don't see how cuttin down privacy would help. Just because they know what TV channel I watch won't stop me from rape, murder, robbery etc etc.
And about the terrorists.....how many terrorist do you have in down under, have u ever met one? No? So why would you worry?
Seriously, why do you feel that insecure? you're askin constanly for more security so you gotta feel insecure? How come? Do you leave your house thinkin "Damn, one of those terrirst will kill me today" ..... I don't think so.
You say you have nothing to hide and I tell you what the problem with the commet is. HUMANS set the line what's wrong and what's right. You might have nothing to hide right now, but that can quickly change. That is why we don't give up no rights, cause a right you gave up you won't get back and the standard, the rules, are set by SOMEONE. That is the point. There might be a situation where you could get blamed for lovin those japanese chicks....you say you have nothing to hide so I assume you don't do drugs, but what about alcohol, do you drink beer groobz? If so, think about it, not that long ago it wasn't allowed to drink liquor in the USA.....