Yes, governments have a history of being unsafe to their citizens, but it's not anything like what it once was, and it's getting steadily better, despite what the MSM wants you to think.
Now I'm not saying it's okay they backdoor all encryption, I just don't think the argument "Government evil" is going to hold water for the average person, nor should it.
A much better argument should come from the, "we prefer guilty people go free than innocent people get convicted, let's apply that policy to privacy" school of thought.