The head of the FBI is very, very worried that people will start using technology — like phone encryption and, presumably, wall safes, or window blinds — that will keep them from watching what you're doing — which, of course, he pinky-swears will only happen if they are investigating Very Serious Stuff, which they would never, ever do incorrectly, inappropriately, abusively, or against you personally, just against all those bad, evil people that they are investigating to keep you safe.
http://arstechnica.com/security/2014/10/fbi-director-to-citizens-let-us-spy-on-you/
And who knows — if the FBI can easily track everything going on with your phone, maybe they can use it to exonerate you of a crime you committed were accused of. It's happened once!
At any rate, compliance will be greatly appreciated. Lack of compliance will be presumed complicity with narco-terrorists, tax dodgers, ISIL, Ebola smugglers, and pedophiles. Because, of course, only the guilty have anything to hide.
> … maybe they can use it to exonerate you of a crime …
Maybe, unless someone decides that keeping the surveillance a secret is more important than exonerating an innocent.