I tend to think that I can actually estimate the NSA's obligation and motivation. Mostly because they are mine, if only in a different area and a different part of this planet. I, too, am concerned with security. I'm responsible for the security of quite important and valuable assets that, if threatened or even harmed, could have a serious negative impact on various parts of the economy and maybe lives, depending on how important some people take their belongings.
I'm not responsible for the security of a country, but of a large enough corporation that maybe this allows me to speak in perspective here.
And there is one thing that is imperative when it comes to security: Your efforts must not threaten your own assets. When protecting my assets costs more than they are worth, the security is not even just useless, it's worse than useless. Because you just wasted more than what an incident could have costed.
Likewise, you cannot protect your assets by throwing them away. Of course you can avoid them being stolen by discarding them, but that doesn't accomplish anything either.
And the NSA is doing just that. What's it worth to defend the USA against terrorist attacks if those attacks would do less damage than the protection? What is it worth to defend the "American way of life" if that very way of life with its liberties and freedoms is discarded in favor of a security theater?