I originally created the plugin several years ago. Then Marco Vermeulen, Feroz Panwaskar, Aaron Zirbes and Jeff Beck started to contribute, and they managed to update it and release the latest versions.
Seems to me that all the people involved on this plugin development had a requirement to integrate with SAML at their jobs (at least that was my case), but I didn't notice more users. And at the end of the day this is open source: the more people using and contributing, the better.
I may need to integrate again with a SAML provider, so I will see if I can contribute again.