Next time you receive a request from the police that you think is reasonable try stonewalling them and see what happens. I guarantee you won't like it.
And as far as the secrecy is concerned: records were kept, that's why you are reading about this.
And these are just the big ones. They've pushed for back doors into iPhones for instance.
I don't care how trustworthy anyone thinks they are. No one should be able to just arbitrarily transcend the law because they are "clean".
If we're going to discuss the FBI in a larger setting I would consider that to be out of scope, to me the discussion is limited to the interaction between social media companies and law enforcement in general and the FBI in particular.