Who is to decide what is in the "interest" of your family and people's safety? This is subjective and cedes power to whoever is in control of the surveillance mechanism. The surveyor may have motives that are not as benevolent as you would like to think.
Or worse still, what if the definition of what is "safe" changes, following some sort of incident (9/11?)
Once they have amassed all this data about you they can mine it to their heart's content and use it to make predictions - those books you read before the "incident" that seemed innocent now get you flagged as a potential terrorist.
