Security methods define the social interactions of nations and their people. As a house divided cannot stand, neither can an overly paranoid state. It's always tempting for those in power to err on the side of intrusion, but the consequences often trigger an escalatory spiral which leads to the destruction of the state's rulers, and sometimes to the state itself.
Like the corrosive action of salt on steel, large, high-powered human security forces erode the integrity of any system of government, devolving democracies into dictatorships, dictatorships into anarchies. The enforcers of security, if not kept in strict check, naturally abuse their functions and in so doing burn out the vulnerable welds they're assigned to safeguard. But how can greater security be bad?
One might say the tone of security governs a country. Whether in an airport, on a train, in a park, on a street, in a car, in a school, in your house, you and I can be held at gunpoint and pinioned to the ground as an indefinite prisoner on mere suspicion and derivation of intent. In fact, this could always happen to us in certain "wrong place, wrong time" situations, but there the safeguards and level of accountability were higher. Now it can happen for no reason at all, with no recourse, with no remorse. If we are mistakenly detained or harmed in security's name, the mistake is an exonerable act no matter how horrifying, how egregious the error. The odds of being on the catastrophically wrong end of the security apparatus are low, but because it can and will happen, it colors every conversation. As Ari Fleisher famously told a reporter after 9/11, you have to "be careful of what you say."
If the security apparatus is in the hands of minimum-wage earners, low achievers, and adolescents with machine guns, then you're living in a second-rate country that actively wants to treat its own people like crap. Pretty soon you'll have to squeeze toothpaste out of its tube at border crossings to prove it's not lethal plastique, senior citizens will have to prove their birth dates to buy a beer, and speaking of salt, people will be thrown in jail for improperly seasoning food.
These prospects would be intentionally ridiculous, yet they aren't. Senior citizens are being carded for buying wine, and a 20-year old girl was jailed for accidentally over-salting a cop's hamburger. (I got carded at a Whole Foods once, refused, and made the clerk bring the bottles of wine back. Chickenshit. If the gray in my beard isn't enough to convince, I'd rather stomp grapes.) And let's not get started on personal care products and borders. See, it's not enough to give followers of Islam a wide berth, to not associate with professors of Arabic studies, to not have "them" to dinner at your home or give to "their" charities. A "take the gloves off" security approach bleeds over into everything no matter how trivial, just as the rust spreads not through one or two sections but through all seams, weakening the welds which hold our system's structure together.
It's simple human nature. If you allow or encourage torture, you will attract men and women who like to torture people. The catalog of human agonies, even after such long practice, is not yet complete.