In all seriousness, as soon as the government starts making a distinction between real criminals and John Q. Citizen we can start letting our guards down on this but until then we should always err on the side of less power and intrusion.
I think you're wrong both in assuming there is an actual difference between "real criminals" and "normal citizens" and in believing that you can ever "let your guard down".
As far as the law is concerned, a "real criminal" is any "normal citizen" who was convicted of a crime. So technicaly you can't distinguish between those two mentioned groups during investigation since there's been no verdict yet.
What you're talking about essentially means placing a verdict before any trial.
As always, people will only promote a system that segregates people if they think they're gonna end up on the right side of the fence.