The internet is a communication method. It's powerful because it's widespread and fast, but it's not a 'tool for terrorism'. The internet doesn't make bombs or create extremism. People do that. Claiming that violating privacy is the only way to fight terrorism is ludicrous. If their goal was to make the US a lesser target of terrorism, they'd be changing foreign policy, monitoring financial flow and looking for equipment and materials. The TSA, for all their paranoia-fuelled craziness, is a much fairer way to stop terrorism than wide-spread monitoring of a communication channel.

As an aside, terrorism as a general thing isn't new. The US was founded with an act of what would now be considered terrorism (the Boston tea party). Americans are so hung up on their constitution, but they don't believe the founding fathers considered these situations when drafting it? Or did 'talking to each other more efficiently' so radically change things in ways they couldn't foresee?