The crux of the debate then is where to draw the line between safe and unsafe amounts of power?
Bush administration is a good example. They just did warrant-less wiretapping. It wasn't hard or particularly expensive. No public debate. And that was a government that more or less followed the rule of law. Imagine one that no longer follows the rule of law.
You don't even need an apparatus. Just send an FBI analyst to pick up Sundar Pichai and Zuckerberg. Have the companies run queries on their own database.
Our government already has the power to mass murder. Obama can order entire continents destroyed. The air force can drop a JDAM on any house in America. The police can arrest any political enemy of the state. The government already has immense power.
Comparatively the sort of privacy issues we are talking about are smaller powers. And like I argued above, they are easy to acquire.
Any government willing to abuse the power of surveillance would be willing to flaunt the law to create a surveillance program overnight (well not literally, but they could do it in months).
I'm not arguing that there is no downside to surveillance power, just that it's not as dangerous as many make it out to be. For example, there is still risk in official abuse by government employees acting rouge. There is risk of data leaks. And smaller scale abuses that can be covered up or that the public wouldn't care about.
But I think the fear that we shouldn't give the government power to surveil because they might go full nazi/communist/theocracic/etc. is silly.