Does Diffusion work with UL spells? Perhaps that is what they are afraid of. It still seems like a non-issue to me and apparently everyone else.

It's also baffling because if they are worried about BLU's support side becoming too powerful (let's pretend for argument sake that this is a valid concern), there are so many ways they could counter this. They could add a duration penalty to diffusion, create a trait that extends duration for self cast blue magic, or add a piece of gear that doubles duration of blue enhancing magic received (reforged Mavi anyone?). There are so many options.

Adding more tiers of fast cast or more fast cast gear is definitely NOT the way to go. Some of the spells already cast very quickly and the job already can't equip all of the traits and spells it needs to.

I don't think a corresponding post was made in the JP forum (I'll check), but I have a feeling no one would be I favor of this adjustment over longer duration.