I for one don't think RDM needs to be nerfed. Simplicity should not mean less damage. If anything the other casters should be buffed imo. It makes sense for black mage to be the highest damage dealing caster, I think everyone would be okay with that. Summoner should be pretty close to RDM and just offers a different flair for those that want something more complicated. I think right now the biggest issue isn't how easy RDM is allowing a lot of people to get close to that Skill Ceiling, instead the issue is with the hugely punishing mechanics of other dps jobs. Make it not so punishing for other jobs and they will be able to reach their potential easier, then if it's still not enough to justify it you could buff the job and I think everyone would be okay with it.