Re: So...FBI wants extra powers then
The FBI boss said nothing to indicate a wish "to read any and all correspondence on your device at any time".
He expressed a wish to be able to do that with a search warrant, issued by a court based on a showing of probable cause to think the phone contains usable evidence of a crime.
As stated, providing a back door is madness and was rejected in principle over twenty years ago.
And, unfortunately for the FBI and others, government resistant encryption has been widely available for use by those with moderate technical knowledge and expertise for over two decades (email and computer files), built in and easy to activate for three years or so on Android devices, and is available as a default for Apple portable devices beginning with iOS8.