In the US, the idea of the publicly funded law enforcement officer can trace its lineage back to antebellum slave catchers.
Much like they now (and forever) frame any perceived difficulty as preventing them from doing their job, they've successfully re-framed their role in society as protecting and serving (people) instead of protecting and serving (property rights), despite that obviously not being the case.
Compare this to the situation in Europe and Asia (or at least the civilized parts like Japan), where it's perfectly acceptable and normal to ask a policeman for directions. And where their role is indeed to protect and serve people (not property).
"Police have the role of protecting and serving people" really does not feel like such a controversial viewpoint to me.
In fact, these high profile cases the FBI et al attempt to use as wedges generally involve someone who has already been caught with plenty of evidence, but the authoritarian impulse still demands more.
As far as laws that can only be enforced/observed by reading people's private thoughts and communications, then yes indeed, why have those at all?
Law enforcement agencies send legal requests to Google and Facebook all the time, and the sky hasn't fallen.
Actually, for all X where X exists, the sky hasn't fallen :)
I think we can agree that, say, putting a chip in everyone's heads that transmits their thoughts to the government would indeed, as you put it, cause the sky to fall. I'm not trying to suggest that outlawing encryption is the exact same thing, but I do believe it would cause much more injustice than it would prevent.
Do libraries not keeping records of who has read what books not allow law enforcement to do their job?
Do prohibitions against arbitrary searches not allow law enforcement to do their job?
Does having to make a plausible argument in front of a judge not allow law enforcement to do their job?
Do individuals not having a number tattooed on their forehead not allow law enforcement to do their job?
Law enforcement continually frames any pereceived difficulty as if it is prevents them, which is utterly disingenuous. Law enforcement's "job" is to operate within the constraints of a free society composed of innocent people, in spite of the extra work from not being able to just shoot the bad guy like in the movies. When they don't respect this, they're merely another criminal element.