In ye olden times, Yoshida or one of the Devs said, back in ARR, that they can't make something undyeable dyeable, that a dyeable version would have to be a completely new item because of the item data flags or some such. It sucks that they seem incapable of addressing whatever roadblocks exist to make a formerly undeyable piece dyeable. It also sucks that the Devs are inconsistent on dyeable outfits from non playable characters like the FF protag outfits, given that the Firion outfit remains undyeable when the other FF protag outfits are completely dyeable even Noctis' outfit which was a contractually obligated outfit design that was kept when XV shifted from Versus XIII to XV, due to said contracts.