It's cut and dry depending on the community.

Some community would defend it only cause there is no for or against. (and that would put them abrasively for AI, despite attempts to be neutral ground)

AI really should only be used as prototyping tools, which to test basic ideas, which you then make a finish product "From Scratch(ed)" with what you've learned.

Devs Have already have enough tools that improve their time when creating, they don't need something that will automatically remove their efforts. (Which like any other development process, could eventually eliminate them as well.)

[Which is why when it comes to legal, it would have to be pushed to have it measured, and limited]

More so, when they already have ways and funds to do it at 100% from the get go, rather than hit generative roulette for hours that will always be missing the artistic edge, and exact creation.(rather than something that doesn't get close to what is EXACTLY wanted.)

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Voicing the Self-Insert/Customizable Protagonist is unlikely to ever come out well for a long time.

People's imagination shifts and evolves over time. Emotes fill the gap enough, and So does combat damage/noise.

(I'm sure some who didn't have an idea of who their character was/is at the start. likely chose a voice that didn't exactly fit their imagination for long. or as the game progressed, changed their view of the character, and how theyd sound. More so when some players likely don't use emotes much at all. so there being a disconnect with any voice at all.)

So the idea for something that wouldn't perfectly fit all players perception of their own characters.
To then expect any Generative Process of today or near futures to do it well.
and then the various/almost endless variations, that don't exactly sound human.
(even if you bring up samples of AI voicing with excessive sighs or grunts or mumbling or uhhs/ahhs that don't really feel natural either. but inserted as a checkmark)

and then XIV doesn't really let you mix or match the voices for one's you like.
[Always locked down based on what the dev imagines to exist within their world.]

It would not only take alot of time(and resources. Development) but the game today would have to adjust for it, it's implementation, any variability, it's coding out of many on the servers (and how it's data gets sent to other players).

Then if they decide to make a Future FFMMO, it would also face the concept of "What do players Actually Care Alot About"

Voices on a Custom Character don't really reach the top priorities.

And in the current game, there is alot more things we want SE/CBUIII to do and implement.

We all know we want alot of them, and some have higher priority as standard.