Why are cosmetics so restrictive?

[RyuujinZERO]

Square's art direction simply knocks it out the ballpark for MMOs; which is fantastic because as we all know, the real end-game of MMO is creating a unique and awesome look that suits your character.

However, as a tank, I find myself stuck having to choose between either heavy pauldrons, flanchards, spikey metal plating, or fluffy civilian clothing and underwear; with no middleground. And I know I'm not alone, a black mage I spoke to recently was lamenting that he could not wear plate armour to create more of a battlemage look; and I really can't see a good reason why they can't. Even Paplymo wears plate gauntlets, and Yda plate greaves.

It's quite apparent that the developers don't care about "maintaining immersion" as the reason, because I can glamour my full plate to look like a bikini - but apparently I can't glamour it to look like a lightweight leather chestpiece from the "Maiming" or "Scouting" pools.

This is especially exacerbated by the launch of Stormblood, where they seem to have really doubled down on the "All pauldrons, flanchards and spikes" look for tanks, with only 1 new set featuring none of those 3 (And that swings so far the other way it ends up in bikini territory), yet gave a whole new wardrobe of varied and interesting looks to the other roles; even the DoL/DoH stuff this expansion is class locked.

Simply put, I don't understand why Square insists on locking content behind arbitrary limits for no clear reason in a sub-based game... anyone?

tl;dr - See title

EDIT: It's also come to my attention that apparently the Chinese FF14 servers have access to universal cosmetic versions of some restricted armours that we don't too. Which is a rather odd disparity