In theory you are right. The problem is that laws change and I cannot predict in what fashion.
What you do today and what is perfectly legal may well be illegal tomorrow. Take, say, smoking. Maybe you're smoking. Now let's imagine smoking gets banned. Well, tobacco is addictive. And if you're known to be a smoker, maybe you should be monitored whether you heed that ban or whether you engage in some illegal activity now that your addictive substance is banned.
And should you have dared to criticize the government in a way that has caused enough waves, this just might serve as the excuse needed to make you disappear behind some bars where you cannot reach those that like to listen to you. And hopefully soon you'll be forgotten and life will go on.
There are some countries, and I'm far from talking third world dictatorships, that are on the verge of heavy unrest. I don't want to say civil war, we're far from that, but there's a LOT of very unhappy and very disillusioned people in many countries that we'd consider first world countries.
All it takes is someone to gather behind. And that's to be avoided at all cost if you're a government, interested in preserving the status quo as long as you can.
So anything to get rid of such people is a good excuse. And having access to data is one way to find something. In case you ever wondered what purpose all those unexectuable laws we're seeing popping up could possibly serve, this pretty much is it. But if you need to construct dirt about someone, you need to have access to his documents.
Everyone breaks the law. Daily. Multiple times. All it takes is access to the proof.