It’s always possible to make a plausible-sounding case for allowing government agencies access to private information. One can always cherry-pick a few cases in which access seems legitimate and for the social good. The fact is, however, that government agencies routinely abuse their powers, are generally incompetent, and not infrequently withhold information that would help clear a suspect while releasing selected information that creates the appearance of guilt. And this is while the USA is not yet entirely a far-right dictatorship.
The problem with the “we need access to stop bad people” line of reasoning is that there’s no place to stop. Clearly, if access to encrypted devices can “solve” crimes then we need to monitor everyone, everywhere, at all times. Fortunately for government agencies, Alexa et al are being snapped up by people who can’t even begin to comprehend the notion of personal privacy because they’re too busy posting images of themselves on social media. So now agencies can monitor people in their homes thanks to the rapid adoption of Orwell Boxes.
In all likelihood, the USA will end up becoming a total surveillance state, much as the UK now has CCTV cameras almost everywhere, tracking people via face recognition algorithms and ensuring that the authorities have an ever-increasing and ever-more-pervasive always-on capability to observe everyone, always.
Which ultimately means that everyone is vulnerable to “persuasion” when the authorities feel it is needful. And when the authorities are controlled by mindless vermin like Trump, that doesn’t bode well for what remains of Western civilization.