@link2xt - The unencrypted subkey option didn’t occur to me, good thought!. There are, I’m sure, use cases where that makes sense.
I come to DC as a long time user of PGP and while GPG users are a tiny part of the digital herd, it is likely that DC’s (brilliant IMHO) use of GPG keys will win favor with crypto enthusiasts. I appreciate an emphasis on ease of use - GPG remains absolutely is too much hassle for the vast, vast majority of users. The autocrypt model is a really solid balance of security vs. convenience that makes GPG accessible and can help make encrypted email a norm rather than an exception - that’s great, no question.
I’d argue that it is possible to support those that have already made a decision to tolerate inconvenience for greater security and integrate them into DC - and that this is a wise strategic decision as security conscious users are likely to preferentially consider DC over metadata snarfing, trust-us “crypto (ish) chat” alternatives. Supporting GPG lights the beacons of Gondor and that sound is the shuffle of all those with framed, Phil signed 1991 floppies of PGP coming to the yard.
There’s no need to afford creation of encrypted keys within DC. But if a user has created an encrypted key elsewhere and wants to use it with DC, it just seems polite and fair to trust they have a reason for doing so and fully embrace that use case as model users of DC. Import the encrypted key, ask for the passphrase, keep it in memory as long as the OS allows, do not write to storage, if the unencrypted key has been dumped out of RAM, ask for the passphrase again. Most people using DC or autocrypt will never see this and never have to deal with the hassle of dooting through a passphrase before reading a message. Those that do need it will very much appreciate being able to.