I like the idea, but not as extreme.

For BLM, spells in combo should be given a 10% reduction to MP cost during active mode. Perhaps more potency or accuracy. Maybe even casting speed?
I'm totally against bringing back movement during spells. Don't want to make it TOO easy.

The ranged autoattack is a maybe. I can see it getting annoying when you're trying not to attack.

For WHM? Perhaps an increase to healing potency and enhancement potency.