Enigmail is far from friction free and no 1-click setup. I still have to go through key generation last I checked. And then publish those keys or give them to friends.
If PGP/GPG wants adoption they need to eliminate those friction points, a TOFU model with automatic key redistribution should lower friction sufficiently but except TOFU there isn't much development in that direction.
>This is exactly what it is doing. PGP/MIME is a thing.
I don't think I ever received a single PGP/MIME email. I don't think a lot of people use PGP/MIME. It's a niche setting for a niche software.
Your desire for "a TOFU model with automatic key redistribution" is well-founded, and people (including implementers) are trying to do something about this. Check out the Autocrypt project:
As for the tools, they seem very easy, especially engimail which IS 1-click setup.
> add generic messages about encryption in alternate mime content bodies and simply encode the encrypted messages into it's own
This is exactly what it is doing. PGP/MIME is a thing.