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

[Avatre]

Let's break it down a bit here.

• The mighty Zodiark, which has been build up as this mighty(evil) entity over several expansions, turns out to be nothing but filler trash for the first Endwalker trial

• For this one, Zodiark isn't whole. There are other shards out there that haven't been rejoined as we stopped the Ascians in their tracks. That is why he was severely weaker than he could have been. Was it a bit of a let down? Definitely, but it brought him(and the most annoying thing) to an end.
  
  
  

• The true cause of the Final Days is a pet-project from an ancient which goes mad after observing countless dead world and possibly causing the death of several world by projecting negative emotions unto them, and is thus dead-set on bringing despair to every world, upon which said ancient goes mad and is now letting her run her course to test humanity if they can withstand/fight despair