Even though I don't agree with everything there (mostly nitpicks and liking a different design philosophy) I love how you did it and I wholeheartedly agree on your approach to optimizing a job. For anyone reading this, read that forum post.
I agree with this as well. Having MP as a resource which all jobs can interact with allows for MP Restoration to be added as a utility. Which can be a way that certain jobs "buff" others and might even create soft synergies between jobs. Maybe a job consumes their MP continuously so they might synergize well with a job that recovers MP continuously etc.
I can only give my +1 here however I didn't play in StB (Started late ShB) so I can't really comment about past versions of the jobs.