I'd say the Ancients were screwed over not because of the nuance that existed where Light and Dark are concerned but more so because of the agency of pretty much every character in the story being sacrificed in the name of trying to push the idea that Venat was 'right'. Well intentioned extremists have always been one of my favourite character tropes but FFXIV forgot about the 'extremist' part of the trope and decided to have absolutely nobody of note criticise the consequences of Venat's actions. Worse yet, they were pushed as a 'necessity' despite deciding to tie Venat herself to every sinister event that took place in the game's story on either a direct or indirect basis.

I agree that the Ancients should have continued to be portrayed as being above the petty squabbles of the mortal races - and their demise being an unjust tragedy rather than something that 'had' to happen. At the very least, I think Amaurot served as a better look into the Ancient world than Elpis. The writers would have done well to sit back and let the story 'rest' for a while before deciding to rush to the finale. 6.0 being another largely self contained expansion along the lines of Heavensward would have been wonderful.