The point is that (being realistic) the terrorists that these measures are designed to thwart are fundamentalist islamists, who would like to see a world run under strict Sharia law. They would like to see the religious police take people away for thought crime, they would like us all to bow down to the proclamations of religious leaders, they despise freedom and democracy. And so, apparently, the best way to combat these people is to give our politicians the right to take away people's freedom without judicial scrutiny?
Sounds like cutting off your nose to spite your face to me.