Here's the thing though, the Empire outside of Ardyn gets almost no screen time, so unless you remember the announcement trailer, you're not really going to think "Hey where did the two old guys go". The fact that Jihl gets screen time gives the audience an expectation, while FF XV gives you no expectations for its story after Altissia.
At no point did Tabate ever think "When Ardyn became the new main villain maybe I should give the old evil Emperor more screen time to explain the plot and not just shove it off to another round of DLC"?
Like maye dont leave most of the plot to the DLC, especially if the other DLC depend on the first few DLC selling well.
Well they put it in a novel so hey you can read it in the Final Fantasy wiki
Final Fantasy XV -The Dawn of the Future- is a novel follow-up to Final Fantasy XV. Written by Emi Nagashima under her pen name Jun Eishima based on a draft by the Final Fantasy XV development team, the novel retells the events of the cancelled downloadable content tetralogy of the same name...
finalfantasy.fandom.com
Wait the Starscourge is a mutated form of Malaria? Am I reading this right? Why the hell would you put something so stupid into your game
O'er rotted Soil, under blighted sky, A dread Plague the Wicked hath wrought. In the Light of the Gods, Sword-Sworn at his Side 'Gainst the Dark the King's Battle is fought. From the Heavens high, to the Blessed below, Shines the Beam of a Peace long besought. 'Long live thy Line, and this Stone...
finalfantasy.fandom.com