The mandolorians were not turned into "tree hugging pacifists", that is only the Concordians. They are a planet inside the Mandolore system, but not the same as the Mandolorians everyone thinks of. There are still true Mandolorians out there, just not on Concordia or Concorde Dawn.
Jango Fett's sister, was a Concordian, i think it was mentioned in Order 66, that was the original idea of why she was catatonic when she was brought to Mandalore
correct me if i am wrong, it doesn't happen often, but it does happen