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

[Theodric]

Agree with everything except Ultima.
He really shouldn't be compared to Lavos or Jenova. Those two are more akin forces of nature that barely look like something you can communicate at all with, which is part of the reason why they are scary. Ultima "looks" scary but is a monotome blabbermouth.
His motives are more stupid than Meteion's, and he literally comes out of nowhere even after the tedious exposition dump he gives.

I agree, though I was referring to the Ultima of Ivalice rather than the Ultima of FFXVI.

I wasn't a fan of how the antagonists were handled in FFXVI but it does match up with how unceremoniously some of FFXIV's antagonists are cast aside.