> E.g., I have one device 'foo' which you already trust. I add a new device 'bar'. Why on earth would you want to verify its key manually when I could just send you the new key from 'foo' which you already trust?
This particular issue is being worked on right now in Riot, and should be fixed early in the new year.
The UI could definitely be improved, but the core team has recently hired a UI designer, so hopefully this will improve in the future. If you have any other feedback that you've heard from your trainings, I'm sure the core team would love to hear about it either in their issue tracker (e.g. github.com/vector-im/riot-web/issues for Riot web), or in the Matrix rooms (#riot:matrix.org or #matrix:matrix.org).
This particular issue is being worked on right now in Riot, and should be fixed early in the new year.