@HuneeBruh to focus on the new characters it's introduced, with Toriel not being awake for Chapter 3, Asgore having a reduced role in Chapter 5, Undyne disappearing as soon as she enters the Dark World, etc.
Even with Gerson, he had only a small role in UT. Why not focus more on new cast?
@HuneeBruh Here's a good twist, then, I think: how would the game's established theme and narrative so far be meaningfully enhanced by Asriel being the knight? What unique ground could be tread that Undertale hadn't already touched on? Especially given that Toby seems to want this story -