What's the point with that quite lackluster story in Endwalker?

[Theodric]

Both out of unfortunate necessity, though. I'm not against the fact that you had to fight and kill the elder primals. I would have been against yet another "Only Mankind is the true arbiter of morality and destiny!" message.

...but that's exactly what we ended up getting, though. Shadowbringers was presented as a battle between two opposing heroes seeking to safeguard their respective people and continue their existence. With the position Venat had put them both in, only one could emerge victorious. Endwalker decided to try and subvert that by pushing the idea that the Ancients deserved to be subjected to genocide because a nutty, unhinged individual decided to condemn them to endure the Final Days and when they didn't react how she wanted them to (with no attempt to tell them what she was worried about) she then opted to murder them all.

I mean, Zodiark was a skin suit for Fandaniel the one time you see him, soooo....

Putting aside the simple fact that he didn't need to be merely a 'skin suit' the game will insist on non-entities such as Meteion, Alpha and Omega as being treated as living, breathing beings...so there was really no reason for the story to break those established rules for Zodiark. He was a being simply awaiting new orders from Elidibus but was performing the task of keeping Etheirys safe in the process.

Furthermore, he had countless Ancient souls held within him. We get a brief scene where they try to speak to the player character but they're quickly silenced. I felt that was missed potential - and sacrificing something inherently more engaging than a lengthy, unskippable cutscene involving G'raha eating a burger or Venat's WW2 style manifesto about why the Ancients supposedly needed to be wiped out for their own good.