You compromise liberties of non-criminals. We have taken a while to understand that it is better to let someone guilty unpunished than it is to punish an innocent. I don't want to reiterate the reasoning behind this here.

It would be two or three steps back if we just ignore this awareness here additionally to all the constitutions that forbid surveillance in the first place.

Aside from the chilling effects from surveillance and state abuse, there are just no real arguments for surveillance. Sexual crime happens mostly in the circle of the victims, mass surveillance is a completely incompetent approach to the problem space.