Really? You're going to start this again?
The current battle system is the remnants of the scrapped alpha battle system. A rushed job in an attempt to make battle feel faster. SE turned a blind eye to the fact that their Rank system was symbiotic with the battle system in the fact that actions = rank up. When they introduced the stamina bar which made taking actions faster, they didn't take into account that they needed to adjust the way we skilled up. Which lead to spamming of skills. In what seemed like a knee jerk reaction, they changed it to our current model: Mobs give set SP. Which leads to necessity to build TP as fast as possible to burn down the mob as quickly as possible because now time=SP.
So what we are left with is the need to spam TP building skills for the sake of using more damaging skills. The fundamentals are fine. Build TP to use bigger and better moves. What's wrong with it is the need to press a button for every attack to be made.
I keep hearing people state they want to be involved in the combat. Being busy doesn't equal involvement. Being involved in the game means communicating with other people, adapting to current combat conditions.
I'm too busy making sure I don't miss a combat round because my stamina bar is resting at full and I'm not taking any actions. Why? Because I'm trying to tell the PT we got an add and we need to deal with it. After all if i'm not attacking I'm taking longer to kill which means less SP.
Adding in auto attack for the sake of TP generation might actually allow you to become more involved with other aspects of the game you are otherwise neglecting.
Have you considered how a console gamer might react to the requirements to be involved in battle? The use of the directional pad to navigate all actions? Do you have any idea how tedious that is?
This isn't street fighter where all your actions are mapped to 6 buttons easily accessed by a movement of your thumb. Or an action game where you have 2 buttons and what ever sequence you press them in determines what actions you take.
That is not how FFXIV was,is or will ever be set up!
YOu might reference TERA as that "action battle system" Did you know you're two main actions are mapped with the left and right mouse button. You use those 2 attacks for a majority of your gameplay. That battle system was set up to be action.
FFXIV is a menu system layed out on a skill bar in front of you. It's not an action game.
The addition of auto attack will relieve you of the duty to build TP. That is all. You are still involved in all other aspects of battle, be it positional, flow or timing of attacks (through use of engage/disengage i.e. toggle)