Many MMOs have interrupts off GCD. Stuns are usually an extra thing for tanks to use during their rotations that makes things more fun and a bit more random. In FFXIV, tanks have to babysit stuns, sometimes pausing threat rotations to wait to use a stun. If the tank is particularly good at stunning, then the tank also has to deal with enemies building stun resistance. Instead of being fun, stuns in FFXIV are annoying.

Take stuns off GCD. Stuns should not disrupt threat combos or otherwise annoy the tank. That's not fun. Warriors and paladins should also have the same stun: instant, off GCD stun with 7-10s cooldown. (Also remove the disabling effect, turn the stun into an interrupt.) If FFXIV wants stun resistance, then design fights so that the dangerous interruptible attacks are spaced out far enough that good tanks can stun them all.