Why did they do this?

[Gramul]

Like many people, I've been busy buying new gear for my higher classes tonite, and I'm wondering how the hell a particular piece of gear becomes a discipline exclusive upon being colored. (Raptor jerkin can be worn by an ARC, but dye it blue, and becomes DOL only?!?!) Arc can wear brass vambraces, so why can't they equip cobalt? How in the name of sanity did SE screw up something so simple a concept so badly? I've spent almost a million gil on new gear, and now I'm likely going to have to sell some of it at a loss because the devs weren't thinking with any degree of common sense.

Strange. I guess they're trying to make gear more aesthetically specific to their respected classes.