He still said he plans to do DLC post launch, which is literally all that a season pass really is anyway, a season pass is just another name for a DLC package post launch, you can not call it a season pass but it will still be post launch DLC. Your argument makes no sense at all nor does it have anything remotely to suggest "wasted potention of good storytelling". Also the fact that you are trying to leverage "good storytelling" as something KH has is extremely laughable. Even worse in that because you are literlaly forced to play a bunch of random side games just to get main story, which is worse than anything DLC could do.
Also KH2 was far more unfinished on launch than anything you could say for XV.
Ok then based on only you playing KH2 and nother else, who is Marluxia and Larxene? None of the DLC for XV are crucial to the main story of XV either so I don't know what that has to do with anything.
Nothing about Ifrit that they added really changes anything other than you getting more backstory for Ifrit, but hey KH instead of explaining things to do with the Organization properly in KH2 instead made some random side game that shows you everthing that happened to Roxas and how he and Axel became friends, which isn't even shown how it happened at all in KH2, nor are half of the Organization even in the main story of KH2, KH2FM added a bunch of new scenes and new bosses and content that expanded the story not any different than the Ifrit or ch13v2 or Royal Pack stuff added in XV, and the DLC in XV serve as self contained side stories the same way the "side games" in KH do, only difference is they released the XV sidestory stuff as DLC instead of as seperate games, and the reason they even justified releasing those KH sidestories as games themselves was by padding them with a ton of filler. The actual "story" amount on KH Days and ReCoded and BackCover is equal to what the three Episode DLCs for XV have, only the XV DLC is just those packed as episodes instead of padded to be like actual games.