Except as stated earlier in the thread healers are 3rd in the race for most special snowflake gearsets behind range DPS and Tanks (And you're never going to get a role get more unique gear sets as tanks.)
Fact of the matter is that with the way most MMOs are made, and FFXIV especially, cutting corners is a must if you'd want anything to come out in a timely manner. Those same guys who have to model and mesh are also modeling and meshing for content years down the line. Before ARR even launched they were already in the concept art phases for Heavensward, we had an almost complete Shiva model almost an entire year before she was ever added into the game. These types of decisions over gear design and who wears what is made months to years in advance.
The developers have expressed that they want to stray away from allowing "out of character" glamours as much as possible. It's part of the reason why they continue to forbid players from glamouring outside their classes. They only tend to hand off sets out of role when appropriate, like SCoB's Caster and BRD sets.
The thread started asking why casters and healers keep getting the same armor meshes when new gear comes out. I'm providing context based off of the design philosophy given out by the developers multiple times and based off the reality of game development, especially one that tries it's hardest to push and release content on a very quick rigid schedule.
