I’m gonna be straight to the point and I’m going to outline some things I feel need to be addressed with the battle system of final fantasy 14.
Let me start with this every monster including bosses should have a stagger meter.
This is a meter by which when full an enemy suffers from being staggered and is made vulnerable for optimum damage of 150-200% and cannot attacked like being knocked down...
-tanks-
I feel every tank class should have abilities that knock down,push back, and corral
The epitome of a tank is drawing focus but combat wise they should have abilities that ensure they can guard a party and keep enemies centered on them and also weaken some monsters.

-dps-
From using the red mage class I realized every dps class should have an escape skill
But also not one that is used like a skill but rather... if you target an enemy and use the target lock on, when using the jump button and a direction you should activate a type of dodge. Depending on what class your playing is the type of action the character does. For ex: a dragoon might quick dodge with his jump ability, or a samurai with a flash step, a monk with a leaping side step but it works to get out of a danger zone and to keep it from being consistently used it would have a 10-second cool down...

-mages-
Now for mages the magic class I feel this relates to my earlier statement with tanks but
I feel mages as well should have attacks that push back, knockdown, trap, and hold enemies, dome barriers with their own hp and trap abilities to ensnare enemies that are too close and melee proficient. An explosion from a fire blast may knock back enemies or comet may knock down enemies, but some spells should hold enemies in place and have combo effects...
Casting freeze multiple times on enemies freezes them then after unfreezing causes slow... but a frozen enemy might take double damage from a tanks shield bash or a monk’s heavy attack skill.

At the same time I feel that certain classes need advantages over certain classes in situations. If your fighting ice monsters or monsters from coerthas then a black mage has the advantage because fire magic... with deserts ice magic etc... but also with other classes a warrior can tank and Dps... a paladin can tank and heal party members... and a dark knight can tank and black mage... that’s how there supposed to be... a white mage might can erect a protection dome that has its own hp based off the mages intelligence...

I feel they should bring back real final fantasy gameplay and not fancy every other mmo gameplay... it would actually make forming parties interesting...