I didn't hate this film, but the ending definitely felt unearned. It felt unearned because you are right, this film is revealed to be a "how would the world react" theme...but only in the twist. And as such, never explores the theme, but elects to use it only for shock.
Unbreakable, and Split really, are both films about accepting what makes you special and different. Every part of these films are keyed into this theme. Glass however, spends a good deal of time seemingly retreading this idea (am I special? Am I just deluded?) Before ultimately revealing the twist...but, again, this affords them no time to actually explore the idea of what society does to people who embrace what makes them special. And as such, the ending falls flat. It's a shock with no bite.
And that's a bummer, because the idea itself was fascinating. The execution was unfortunately below-par.