That would be a question for Bryan Fuller. He’s recently started to talk about this stuff, so maybe we’ll get an answer some day.

One thing I do think someone said along the line is that they wanted to establish why the Klingons and Starfleet hate each other so much in TOS.

I’ve said it before, and I’ll say it again: if they ever do an oral history of the development of that series, it will be a juicy read.