So, this is a rather complicated subject to broach. There is no easy, or simple way to explain exactly why this is a bad mechanic, as there is no one thing that it does wrong, and there's arguments it does things well. So I will try my best to simplify the problem down to its basic components, and then when people inevitably want it fleshed out, build upon it later.
But fundamentally, AF/UI timer is a bad mechanic, and it's bad for a number of reasons.
- AF/UI exists to serve 2 functions. Provide structure to the boom-and-bust rotation, while the timer provides structure to the AF3 rotation of the class.
- The mechanic is strictly a skill floor mechanic, not a skill ceiling mechanic. Failing the timers mechanic locks you out of your core rotation, and the reward for success is...your core rotation.
- It serves as the third layer of punishment. The first layer is stopping your GCD from rolling, the primary skill check of the class, and the second is failing to have instant cast GCDs to keep the GCD rolling while moving.
- This third layer has an excessive amount of punishment. In addition to the failed first and second layers, you also lose polyglot progress on top.
- This design came about because an old ARR mechanic was just constantly expanded on without any concern for how it would impact the skill floor of the class.
- This also creates poor quality of life problems, such as needing to spam Umbral Soul between pulls in dungeons or when a boss goes untargetable.
- At its most severe, it turns the class into the only class in the entire game as of Endwalker that is severely punished simply because the devs want to add gaols, stuns, or cinematic cutscenes to boss encounters.
- And finally, this is exclusively a layer of punishment, not a reward for handling it well.
That last point should have some expounding of why it's the case. The reason it's strictly a punishment is the same reason DRKs are complaining about TBN. Your reward for executing it correctly is doing your DPS rotation exactly as the devs intend it to without any accomplishment in terms of skill. Your punishment for failing is to have some wrench thrown in the works of your class. That is to say, your rotation shuts down for failing it. You are set back not a slight bit, but substantially. And no matter how well you execute it, the rewards for proper play belong to other skills, primarily keeping the GCD rolling. Not from the third layer of maintaining an arbitrary timer that doesn't need to exist. You will always feel better about outsmarting a boss mechanic by prepositioning better, and it's a consequence of keeping the GCD rolling that AF/UI timers stay on track, not a consequence of managing the timers correctly.
The final bit, the insult to injury, is that AF/UI timers aren't needed to get the exact rotation the class has now. By doing something as simple as making F1/Paradox give you 3 stacks of umbral hearts, forcing umbral hearts to cast fire 4 (and allowing them to overcap because there's no reason not to for the purposes of this thought experiment), you can structure the rotation exactly as the devs wish to without needing this excessive layer of punishment on top.
This is the last class with punishment for boss downtime, especially cutscenes. It is the last class with insanity levels of punishment for failing its core rotation even slightly. It will still be punished heavily for want of these timers. Why do they still exist?