At this point, despite those saying otherwise on each side of the fence, BLUE has to be a 'trial' of limited jobs, and will have to be expanded to allow them to be used in more content.

While they had alluded to just this by saying that the Masked Carnivale is just for us to 'get used' to Blue Mage first, and it will be significantly expanded with greater rewards, I feel this alone won't be enough, even with raising the level cap.
They need to allow BLU in MSQ, Squadrons and Deep Dungeons at the very least. Possibly PVP too.