Hey HN, I'm one of the authors on this paper. I'd be happy to answer any questions.
Have you approached the developers of both Mailvelope and Gmail to discuss these improvements? How did they respond? Also, have you participated in usability discussion with the OpenPGP developer community at large? Any insights?
I ask because it seems like everyone who isn't very active in the OpenPGP developer community thinks that usability is a high priority. But, in my experience, when you start to bring up the topic of user-friendliness in the mailing lists, you get resistance or apathy. It seems like this is a problem of culture and incentives. How can those issues be addressed?