I believe that liberty is the only genuinely valuable thing that men have invented, at least in the field of government, in a thousand years. I believe that it is better to be free than to be not free, even when the former is dangerous and the latter safe. I believe that the finest qualities of man can flourish only in free air - that progress made under the shadow of the policeman's club is false progress, and of no permanent value. I believe that any man who takes the liberty of another into his keeping is bound to become a tyrant, and that any man who yields up his liberty, in however slight the measure, is bound to become a slave.
-H. L. Mencken
The way I see it, if terrorists with the determination of those that committed the 9/11 attacks wanted to strike - they still would have even with these measures in place. The core of Al-Qaeda had a strong technical arm, one which has sufficient knowledge to bypass government wiretaps (ie. use encrypted VoIP), and other such technical measures. Let's also not forget that the 9/11 terrorists had legitimate passports. The problem wasn't that they stuck out of the system, it was that they knew how to be part of it. The FBI's failure is separate to this whole issue of warrantless wiretaps.
We should not blame those that wanted to remove police-state like behaviour from our system. Wiretaps to any citizen, without due cause, is one such instance. Rather, we should blame those that didn't seek to target the cause. If you are to associate those that seek to better American lives with terrorists, than it is not they which are most detrimental to American society - but you. You who scaremonger. You, who has such a black and white perspective of the world that it can only be broken down into associating pro-American populace with pro-terrorist.