I think that's the important insight behind the success of ZMQ. Pieter Hintjens understood that a software library had a social as well as a technical context. ZMQ was built to be a delight to work with, not just a technical achievement. I have lots of respect for Sústrik, but I get the impression that he's willing to sacrifice everything else to have the right implementation.

Really, I think it takes both a Hintjens and a Sústrik to make something great. (Or a Lennon and a McCartney, a Jobs and a Wosniack, a Rodgers and a Hart.) There's a tension between giving people something with integrity, and giving people something they'll love.