Comment by AdmiralAsshat

FWIW, UX plays a big part in controlling adoption. Apps like OpenSignal/TextSecure for encrypted communications make the whole process about as painless as possible. I downloaded TextSecure for Android and registered my number. I made my girlfriend download OpenSignal for iOS and register her number. I opened the app and saw her on my contacts (TextSecure will tell you which of your phone contacts already appear to have the app installed) and sent her a message. Boom. We're done. All of the tedious key-exchanges and whatnot were completely behind the scenes and we never had to deal with it directly. Those options are still there, and if I ever migrate to a new phone we'll probably have to do some kind of new exchange, but otherwise the "fun" of trying to manually exchange PGP keys was completely behind the scenes.