[asteroidburger]

It's much safer to export a key one time and import it into a new machine, or store it in a secure backup, than to keep it just hanging out on disk for eternity, and potentially get scooped up by whatever malware happens to run on your machine.

[Nextgrid]

Any malware capable of exfiltrating a file from your home folder is also capable of calling the export command and tricking you into providing biometrics.

[asteroidburger]

Not necessarily; "read file" is very different from "execute command." The biometrics part is a substantial lift as well.