I don't know why they didn't make Dagon playable, they added Jogo and Hanami, why not Dagon?
Even his boss fight felt kinda unfinished and short.
I feel like the boss fight would have been better if they added some sort of objective to it, they could have had Megumi show up in a short cutscene, and you would have to defend him from Dagon while he kept the hole in Dagon's domain open so the players could escape.
Caption this Meme