Government surveillance is crucial for effective counter-terrorism, counter-intelligence, foreign intelligence, and law enforcement. Government surveillance contributes to an increase in law and order of nations, and an increase in information, allowing these to faster develop, make better collective decisions, and defend itself when under attack.

Opponents mention that counter-terrorism is not effective for all cases of terrorism, in effect arguing for an increased and more efficient surveillance. "They were already on some watch-list.", of course, mass surveillance put them there successfully.

I hear of surveillance abuse, where privacy is violated (spying on ex-girlfriend). But, like the police has a monopoly on violence and can physically restrain your freedom, so has the government a monopoly on violence of privacy. If you deem your country incapable of holding that responsibility, I guess it is time to move to a country where the US government can gather even more than your telephone meta-data.

Finally, that we could end up in a totalitarian surveillance state, is a pessimistic projection akin to adversarial AGI or all police deciding to start abusing and shooting random citizens.