The usability question is crucial for secure comms on a NSA-infested internet - it must be "easy" for non-technical people, but such as to not obscure anything,

The usability question is crucial for secure comms on a NSA-infested internet - it must be "easy" for non-technical people, but such as to not obscure anything, nor impair configurability, for more astute users. But usability is a posterior issue. The first thing is to get the principles right, then usability can be applied by putting on the right interfaces. And I don't think there is any consensus about a good design yet. See my reply on another comment about the design of this system.