If we really need an action for MP recovery, I would propose bringing Celes' Runic (FF6) ability in to RDM's arsenal. Of course we would need to adapt it better to FFXIV, so perhaps it can be a oGCD that every 2-3mins that lasts for about 20secs and it returns a portion of the damage dealt back as MP. It could be a buff that effects RDM only, or it could potentially be a party wide utility, so Bloodbath for everyone... except it's MP instead of HP!