The whole argument that White mage has more healing skill is a joke, because currently healing skill matters very little in the cure formula. With the advent of the cure staff with potency +23%, which any serious healer should have, plus all the new cure potency gear that came out in the past year, the cure potency argument is invalid as well. Cure potency caps at 50%, so the fact that white mage could get 60% or whatever and RDM only 50% is fairly pointless as well.

The reason white mages and SE apparently think Cure V may imbalance the healing jobs, is white mage was marginalized to a degree at 75. I been playing since 2005 and I remember well things like the airship fight and our white mage being told they weren't allowed to come because only red mage could heal that fight. (The white mage wasn't me, I only had black mage at that time. ) That advanced to my limbus shell saying white mages were never allowed in limbus except for bosses, on to Salvage where it was red mage only as well. Of course experience was the most egregious example of white mage being excluded.

SE attempted to rectify this with the solace and misery adjustments, but even at 75 white mage was a second class healer in some people's opinion. So just dumping Cure V on red mage and scholar, who bring mp longetivity and high tier nukes compared to a white mage, may make the balance skew away from the job whose only purpose is to heal. Will the cureskin update, the advanced bar spells, the curagas, etc make it so white mage is still the preferred healer if scholar and red mage get Cure V. I am not sure, maybe, but right now its a chance a lot of white mages, and apparently SE for now don't' want to take.