All sequels are cash-ins.
Most movies, just like most games, have crappy plots and crappy character development.
You should see some of the shit I've had to sit through in my film classes.
I didn't say the movie was Citizen Kane or anything. It's fun. Is it okay for a movie to just be fun instead of being the pinnacle of artistic achievement?
I'd rate Super Mario Bros. a 7.5 and The Wizard a 7.0.
I've never seen Kangaroo Jack so I can't rate it.