But they perform their functions with starkly different methods. RDM vs BLM isn't just about how they perform against each other, it's what they do to achieve that performance; in other words, you can't play a BLM like you would play a RDM or SMN, and likewise playing a RDM or SMN like a BLM (or indeed, a RDM like a SMN and vice versa) won't net you the best results. You bring up how it would have to lose White Wind and Mighty Guard's current implementations--true, it would, but they could also be reworked to be an in-combat "Learn." Change Mighty Guard to be like Third Eye, where you take damage and this opens up a few options for reprisal.
White Wind (at the strength of a medica perhaps) could be one of these reprisals and bring a light heal to the party, and another of these reprisals could be one of the Primal's signature attacks, like Mountain Buster or something. Another route would be something similar to The Blackest Night; Mighty Guard puts up an hp bubble that if popped generates resource for BLU to use its stronger blue magicks like primal attacks. Make White Wind into a medica-like spell that costs this resource (we'll call it blue mana) as well.
Yet another route would be to make it more like manawall--a larger hp shield with intent to keep the caster alive through heavy hits for some positional cheesing. Or like FoE from Monk--a flat 10% damage mitigation that would either increase resource costs while up, cost a set amount of blue mana every server tick it's up, and/or cause a damage penalty.
Or for a support ability, Mighty Guard as a tank cooldown you can throw onto the MT. Works like palisade+apoc at the same time with the same cooldown as either of them, and optionally costs blue mana to cast onto the tank. Maybe 1/2 palisade + 1/2 apoc. Maybe 1 or 2% damage mitigation on the whole party for a lowball as yet another alternative.
There is probably much more that could be done with just these two abilities too. They don't have to be super tankstance and a broken-tier heal. All this to say...
Bringing it in line intelligently would not destroy anything. We're beyond the ability to do that barring major overhaul now though, so we have to put up with limited BLU. But there are a lot of things they could have done with an unlimited BLU while retaining its identity.My point is bringing it in line will destroy what it is. It would bring up the issue that healers have with identity - it will be interesting to see how they handle Dancer - I imagine poorly >.<