I wish people realized that privacy and civil liberties exist regardless of guilt. Rights like freedom of speech, due process, and privacy aren't just for people doing something wrong. They're foundational protections that exist to prevent abuse (by cops, too).
Outside of that very narrow context, they may kindly deal with my communications being secured by default, because if there is a path they can use to decrypt my data, the criminals can also find, exploit, and use that same path. Rather easily, as it turns out. (See: various data breaches, password leaks, company after company getting caught with unsecured S3 buckets containing encryption keys, etc etc.) It's not the law I'm hiding from, but those individuals who would steal every one of my digital assets given the opportunity.
In the specific context of Android, the thing I'm trying to dodge isn't even legal snooping or criminal activity, but specifically marketing. Google is terribly interested in my browsing habits, and so having my smartphone not run their services at all is an excellent way to reduce that flow of information from my device to a third party that I don't particularly trust.