I'd never thought about this, but it makes a lot of sense. We watch the end of the world again and again and each time a white knight rides in and saves us all at the end, of course we become conditioned to think that whatever we do wrong or whatever the disaster is, someone will always have a miracle solution at the last minute.
As long as Tom Cruise, Arnie, and Bruce Willis are alive the world can not end by disaster.
Once they pass on though, all bets are off.
I think they need to go down the route of horror films and just have a few that end up with a miserable and sad ending. Not too sure if people will take it seriously though.