The main theme of
XIV, so far, has been
letting go of the past to make a brighter future. Every major antagonist has something in their past they simply can't let go of, and it drags down others; they all live in the past, while the protagonists fight to make a better future.
- Garlean Empire: pugnaciously attacks other nations due to their mistreatment centuries ago instead of letting go and becoming a constructive member of the international community.
- Nidhogg: eternally attacks Ishgard for Ratatoskr's murder instead of letting go, to the point he practically emulates the Ascians and becomes a spirit possessing a mortal.
- Archbishop Thordan: refuses to let go of Ishgardian history and traditions after Nidhogg's initial defeat.
- Ilberd: refuses to let go of Ala Mhigo, dragging half the world into a war to liberate it whether they will it or no.
- Yotsuyu: refuses to forgive Doman culture for giving her a bad shake.
- Vauthry: refuses to give up his self-indulgent paradise, fleeing to make a new one after losing control of Eulmore.
- Ascians: refuse to let go of the memory of Amaurot, willing to sacrifice the entirety of mortal life to bring back their civilization.
About the only one that doesn't qualify is Zenos, and he's a sociopathic killer.
It's also well-demonstrated with Thancred and Ran'jit's differing attitudes toward "Minfilia;" while the former eventually lets go of "his" Minfilia and acknowledges Ryne has value as her own person, Ran'jit refuses to do the same.
This really comes to a head during final fight with Emet-Selch / Hades. While the Scions' attacks don't even faze him, the following exchange does get a rise out of him (paraphrased):
Urianger: To make the best of all futures... be this not also thy purpose?!
Emet-Selch: Do not presume to speak of
my future!
... and finally the Warrior of [Light/Darkness] and Ardbert's line to him right before the showdown:
Ardbert / PC: This world is not yours to end... This is our future. Our story.
To the point, Emet-Selch refuses to let go of the past, going so far as to make an illusory replica of it to live in. He
literally lives in the past. Again, nearly every villain (or antagonist, if you must force the distinction) does something similar, while they're usually juxtaposed with someone who has or does let go of the past and is happier for it (Eorzeans put aside their differences to make a better future for the entire region, Hraesvelgr lets go of his hatred and despair of mortals to make a happier future for man and dragon alike, Aymeric exposes the truth and passes reforms that shake Ishgard to its core but ultimately leave it a better place, Hien willingly floods Doma Castle to free it from Imperial tyranny, etc.). While the villains do have sympathetic motives for their actions, they are all ultimately trapped in the past; the heroes conversely fight for the sake of the future, and the villains who
do let go of the past in their dying moments are easily the most sympathetic (Yotsuyu, Emet-Selch).
This ties back to Hydaelyn - she does not exist to determine or dictate humanity's future. She exists to make sure humanity
has a future that doesn't involve becoming Zodiark chow, not what that future will be.
So the "Reins of history in the hands of man!" shtick people love to use when justifying deicide in
Final Fantasy doesn't really apply to Hydaelyn. She also seems to be unsummoned (residing in the aetherial plane), so she's no danger to the world.
Ultimately there is
no reason to call for Hydaelyn's death, since she is benign at worst. Hydaelyn is the legacy of the ancients who wished to give the races of man a bright future; to say she should be killed for the sake of man's future is... disrespectful and conterproductive, I think.
Zenos trying to hijack her and/or Zodiark's fragments for power notwithstanding.