I suspect the non-standard JSON license was in part a strategy to encourage third-party implementations, so that the format would become a standard.
(W3C standards, for example, require "multiple independent implementations to proceed along a standardisation path". https://www.w3.org/TR/webdatabase/ )
Ultimately though, if you put a non free license on your libraries, somebody will cry foul, fork it, and evil will still happen.