So, anyone feel like this should have been a bigger deal...? (SPOILERS!!!)

[linayar]

I know they were described as the "hearts" of the primals since Shadowbringers, but we never really learned what that meant – my impression was that it was more of a core for the primal to form around, maybe influencing its personality, but not simply being the same person now in control of a more powerful form.

I suppose our closest reference is incarnate summoning, where a single person draws the primal's power into themselves, but a heart seems like it would be the opposite: being the core on which the power called forth by all the summoners together would coalesce and become something vastly greater than a single human mind.

And if Elidibus is to Zodiark as Venat is to Hydaelyn, the very mind and personality of the primal but set free to wander, the story has never treated him as such. Even once it was revealed that he was a primal, an essence drawn out of Zodiark, he was treated as something separate and not (at least with enough emphasis) the key functional part of Zodiark himself. For all we knew at the time, what was called forth might not have even been the real Elidibus but a copy produced by the wishful thinking of his friends while the real soul remained within Zodiark.

What do you mean? Elidibus was something separate because he separated himself from Zodiark. In that way, Zodiark was more like a husk. The fact that Elidibus still existed as himself instead of being completely consumed by Zodiark hints at this.