Jigsaw didn't have the right.
He played God when he had no right. Yes those selfish unlikable people in ALL the Saw movies didn't appreciate their lives, but what has it got to do with you? Someone needed to tell Jigsaw that because he took it upon himself to teach these people (who he doesn't even know) a lesson.
Bottom line whether they appreciate their lives or not, it's between them and God. Same thing with the awful flick "Phone Booth" a person forces someone to admit their wrong ways, that's not your choice, it's up to God to handle them. I know "Phone Booth" isn't the same as this film, but the bad guys have a similar motive.