@Abedeus Personally, I see the Kiryuu-vs.-Fallen Black encounter as the closest thing to a real 'final fight' that the series could've given us while sticking to its guns! I'm inclined to agree with the story itself on the point that Andou and Kiryuu having a full-blown brawl just never would've made sense, narratively or thematically, and going back to show us the rewritten-by-Andou-and-Kiryuu version in full detail would've felt superfluous to me since by that point, that narrative and its themes were already very firmly concluded. It would've been a (presumably lengthy) digression into a completely different series, essentially, and while I would absolutely love to read that digression, I also deeply sympathize with Andou's speech near the end of the novel about how it's far better to go out at your peak than to keep dragging out a story until you have no choice but to end it
Which is all to say: I see your point, but man, personally? This is exactly the ending that I felt this series needed, and I'm extremely happy that its author had the guts to commit to everything he'd set up and go through with it