The most interesting origin idea is that it was mostly deliberate. From the Internet to cell phones, we're always inventing things to enable us to work together more easily. Itcould be awesome to be part of a hive mind, capable of understanding things an individual cannot comprehend. I'm not even sure how it all went wrong, if the drone brains are an important part of the Borg mind, why are they so happy to escape individually from what they create collectively? Yet a big bureaucracy can be like that too.