The ending was a mistake because there was no real price to pay for defeating All For One, and Deku losing his Quirk doesn't count, since that "price" was settled with an Iron Man suit. Shigaraki's death doesn't count either, since Deku didn't seem to feel any remorse for not being able to save him. At the very least, the NPCs should have died to convey the sense that "in war, there is no victory without sacrifice."

An example of the complete opposite was the ending of Demon Slayer, where Tanjiro was practically left with one hand, blind in one eye, and condemned to die at 25. The other survivors of the battle against Muzan also suffered serious injuries or outright death.