If you assume that most governments have been doing that to various degrees since forever, and the only thing that has changed is the degree to which the information can get out, and the ease of anonymous whistling-blowing (which still carries too much risk, however it's arguably better than it's ever been) - seen in that light, you might suppose that while things seem to be getting worse, in fact they are getting better precisely because we're more aware of these various atrocities than we ever have been. It's possible to be very optimistic for the future while also outraged at what these inhuman murdering savages are doing in our name.

For example, I'm sure now that the CIA tortured countless Vietnamese during the Vietnam war, Iraqis during the first Gulf War, and you can apply this to the Korean war, WW2, basically as far back as you want to go. We just didn't know about it then, because it was easier to silence journalists and neutralize (murder) whistle-blowers or suspected whistle-blowers without the general public knowing about it.

FWIW, I am in the pessimist camp as well, in spite of my reasoning here, but just barely. I think probably things are actually about the same as always, but perhaps with the broader awareness we're just starting to see, that is just beginning to change. It's comforting that at least I'll probably know one way or the other within my lifetime.