Earlier quoted context omitted.
Honestly I'd like to see one of the webmail providers do a decent attempt at gpg. The web migrated from a primarily unencrypted state to an encrypted one - it's not impossible with the right UX.
The web is encrypted in transit but most data is probably stored in an unencrypted form, much like email.
Yes, it would be possible to encrypt email too but it would involve changing every email client and server there is, and there are quite a few of them. And a public key repository for everyone to be able to find the correct key for each receiving adress. Mailing list servers and other group mail would be particularly fun to solve.