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.
spoiler: 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