For the most part, no one cares whether they're using something that is open source or proprietary. Most people don't event care much about abstract concepts like "security" or "encryption" when it comes at the cost of their real goal -- communicating with family and friends. Once some secure platform is as easy to use[0] and as prevalent[1] as Skype or Google Hangouts, maybe people will start using them.
[0] A sibling post suggests setting up Jitsi with IPv6 and starting the program with the -6 parameter to fix some connection issues. I would hope it's clear why needing to use certain command line parameters and understanding "the implications of having a public address" to use a chat program makes it a non-starter for a vast amount of people.
[1] As it turns out, advertising and marketing matter! You can't have a popular chat platform if no one knows you exist!
