NOTHING. ABSOLUTELY NOTHING. Stupid question. You might want to consider that the government is breaking the law of the land and spying on citizens. That is unconstitutional.
Well, nothing in this world is entirely bad or good. I thought, if it all became public in a hundred years or so, we could gain insights into sociology and whatnot. Like psychohistory could actually exist because of this data. Also, it 'levels' the playing field quite a bit if the data is publicly accessible; the world is not only flat, but concave in that scenario.