Curate, connect, and discover
Shigaraki's death would have indeed been better if he ended AFO in the end. I mean, when AFO went on a rant about how he controlled and puppeteered (is that even a word?) his whole life, I was half expecting him to fight back with utter destruction and anger. Because we know he can feel anger and hate (somewhat). But for it to be so anticlimactic and all.
I wasn't even mad about Izuku becoming a teacher. That was honestly a quite good call. To teach young and bring them on the right way... right into the manipulative and broken system, he fell into himself. Yeah, the last part didn't sit right with me. But for him never to speak uo about Tenko and just letting everyone believe he was a full on Monster, which had always been this hateful creature (he was evil, but I wouldn't call him a monster right away. AFO is a monster im my opinion)
Friendly reminder that Shigaraki being saved ≠ his actions being forgiven.
He still deserves to be saved from AFO and from himself, regardless of his actions. That doesn’t mean all is forgiven, though.
It would be so meaningless to just kill him, because what message would that send? It would be far more meaningful to save him.