very true, and thank you for pointing this out. this is an intentional design decision - you can see me rationale here: https://j3s.sh/thought/storing-passwords-with-age.html
it boils down to exactly what you noted - disk access is game over in most cases anyways, and i like the convenience of plaintext on the disk.
i will be exploring the yubikey model that filippo recently outlined though https://words.filippo.io/dispatches/passage/ - so stay tuned! :D