You mentioned most of it, mitm, family/friend access to files, losing of devices.

Another thing most people overlooked would be in the corporate side of things, compliance is another factor to look at. Data protection policies etc.

How about hosting your encrypted files in another person or organization's infrastructure? Cloud services is a huge thing now, AWS does take measures to encrypt & safe-keep your data but it's best you add your own 'layer' as well!