Some people do use PGP, but they pay for it or it's an internal component in a larger system. GPG, the OSS version does have a sucky interface, but that's not the real issue people don't use it, there's three others:
1) Most people don't give a shit about encryption 2) Most people are too fucking lazy to understand/use encryption (Not being cynical, this is reality.) 3) Writing good encryption software is thankless and discouraging. There's a ton of commercial companies that use SSH and GPG that haven't donated squat to the developers.
"Did any of us make better encryption tools, despite there being available encryption libraries? Not to my knowledge."
You don't work where I do. I wrap GPG in another layer of software to make it more usable to the above average folks at my job. It's mainly limited to automated processes.