Hmmm, going by what the OP says then can BST have a pet that can cast tier V nukes, or one that can buff and heal? What about a pet that can be activated and deactivated without cost? How about a pet even that will stick to the target I tell it too rather than attacking the target it has hate on?
All jobs are different and have different abilities. If SE went with what the OP suggested then they might as well merge all pet jobs into one job and be done with it. People moaned enough and they nerfed BST pets TH, as I stated in another post if they applied the same logic they used for the nerf to PUP then the automaton should only be able to cast tier II spells as it is not a BLM or WHM.