Society just need to decide how it wants to play this because its an either or proposition.
There is no technical encryption protocol that works only for the good guys. Unfortunately the legislators are too thick to realise this simple fact.
If I hired a messenger to take a spoken message to my partner across town, the same applies. Nobody has any right to interrogate my messenger and he has no obligation to answer.
If I send electronic messages it should be no different.
The fact that interception and surveillance is possible doesn't suddenly make it obligatory.
Technology is power, in whatever form it comes in from weapons to education to communication. That power makes law enforcement more powerful and criminals more powerful.
Law enforcement wants it both ways. They want the increased power of their own encrypted communications, their own education, their own better tools and techniques AND they want to use technology to take away power that their supposed adversaries wouldn't have even been able to lose before the tech existed.
The technology exists. It can't be taken off the playing field. It doesn't matter how bad the "bad guys" are, law enforcement does not deserve that much power in a free society. The power balance between the state's monopoly on force and the people needs to be maintained. If it is not, abuses are inevitable.
Basically, it says as soon as you involve a third party - in your example, a messaging app - you can't expect privacy and therefore law enforcement doesn't need a warrant.
If law enforcement had to get warrants for all of this information from services, providers, and vendors, they'd be forced to a) be more selective and b) move slower for judicial review. Both constraints would significantly improve the situation.
But my phone is my voice, my memory, an extension of my mind in many ways. What is "me" and not a third party extends to the actions I take with my phone.
If we can just say my encryption key with a password in my brain is "me" and not a third party's (which can be true with tech setup correctly) then everything is fine. What I give to the third party is not "private" but acquirable without a warrant. But what I give to that third party is cyphertext. You can read my encrypted messages all you want... in their encrypted state. The decryption keys are private parts of my person and the person I am sending the message to.
Now that I think of it, the idea of end to end privacy never really was a thing before we had ubiquitous encryption. Involving a third party always meant that you were vulnerable at that third party. So, I suppose that you could implement laws that dissallow E2E encryption, but still allows encryption from the client to the service -- allowing the service to record the data if presented with a warrant. Now that I think about it, the "wire tapping" code in the telephone switches were literally a legal requirement for selling the equipment otherwise they would never have convinced me to write the code! Now that I'm older and wiser, I'd never do it again... but I kind of understand the symmetries....
In the US the odds of dying in a terror attack have remained historically low since the mid 1970s.
Specifically, it's between 1:12M and 1:40M - about the same as picking the correct inch between DC and NYC.
Conversely, the odds of a US citizen (who is not suspected of a crime) being inappropriately surveilled is near 100%.
How to play it? Prioritize real threats over the nearly imaginary ones.
It should be straight up impossible.
In general I have seen that if people are smart enough to get people to vote for them, they probably have smarts and leadership skills not dissimilar to business leaders. They very likely understand what encryption entails. They probably don't share your values on whether it's a good thing.
Backdoored encryption is an interesting concept, but suffers from the problem that the bad guys could get their hands on the key.
But could there be another way? Something like k-out-of-n keyholders have to agree for the backdoor to open. Shamir's secret sharing could do it, but has the drawbacks that it's one-shot and that someone has to know the key to set the scheme up. You want every investigation to require a new k-out-of-n agreement.
Ultimately we ought to design society so that a large group (legitimate protest) of people can defy the government but a small group (criminal gang) cannot.
For example, a better measure might be the nature of the harm, if any, done by the defiant group.