from all the noise.
Most important and possibly quite likely is that the information gathered is used to target those who exercise their right to peaceful free speech and speak out against our government. Those who assemble peacefully to protest certain government policies could be subjected to intense scrutiny without good reason.
Freedom of the press is essential to our form of democracy. In the wrong hands surveillance data could enable the government to find our a reporter's sources and silence them. Gathering data on a newspaper's editors could uncover personal details of their lives that could be used to prevent them from publishing stories that would embarrass those in power.
Gathering files on all the people we elect to represent us might enable a powerful few to gain control over Congress or even our President. There are few saints in public life who have absolutely nothing to hide.
Of course meta data might be used to stop terror plots. Unfortunately the well trained terrorist will be aware of our data gathering abilities and will find ways to bypass it.
If you suspect this could never happen I suggest that you do some reading about the Nixon Presidency and also J. Edgar Hoover's career.
Information is power and power corrupts. Without proper oversight and regulation, the NSA data gathering ability could enable a select few to gain power over our nation and we might not even realize it. In fact this may have already happened.
The problem is how do you insure that the data is used properly and not abused to gain power? I really have no idea of how this can be accomplished.