OP means they aren't in and of themselves a problem if the citizens do their job and hold their democratic government accountable and force it to abide by their collective decisions.

I don't agree, though; I think secret surveillance is in and of itself anti-democratic. However, OP is correct too, in the sense that once it is revealed that secret, illegal surveillance is going on, if the subjects of a functioning democracy don't care or take any action, that is probably even more corrosive to a democratic state (since presumably there will eventually always be people like Norden^W Snowden, and nothing stays secret forever).

In my opinion, in a real democracy the citizens are not passive voters but a vigilant, armed (at least in the US) populace that holds their representatives accountable and vocally prevents unchecked accumulations of power or other undemocratic tactics (i.e. the electoral college turning into a two-party system). In my utopian view of what a democracy should be, a revelation like this would result in a very significant portion of the people speaking out and actively working to squash the surveillance system, putting the system to work instead of threatening it. Of course, such a society wouldn't let the surveillance situation progress so far and if you view democracy as a voting populace, not an informed one, my argument isn't convincing :)