Do we want to live in a world where the trains we ride every day, or the planes we fly, or the building we work in, or the school our kids attend, is subject to attack at any time?
That is the world we may live in without any surveillance and covert operations.
Personally, I would accept those risks, but only to a certain extent, because I dont know how I would react if it happened TO ME.
Seems to me that our society now is so apathetic, so accepting of anything goes, and so selfish, that evil doers can go undetected until you read in the paper how "good a neighbor they were, but they kept to themselves". Heck, most of us dont know our neighbors anymore. In "the old days" that wasnt the case. Maybe Im just becoming the crotchedy old man, but I bet thats a part of the problem.
People with evil intentions dont stand out anymore! Probably most of the time they could practically announce what theyre going to do and like a car alarm in the parking lot, because of political correctness, they would get ignored. It has happened. People have turned a blind eye with excuses like "oh he is just ranting" or "he's entitled to his opinion, its a free country"
Our society is such that things slip through the cracks way more than they should. Not saying that people should be ratting on neighbors for every dumb comment they make, but common sense definitely has a place here, and really knowing whats going on around you, and being alert, is as important as ever.