Why do adults criticize movies not even meant for them?

I think of this a lot too. I think it's to help parents possibly save money taking their kid to it, and wait for DVD. It's their money, not the kids. You can't really ask why they bash movies without saying why they praise them (e.g Toy Story 3 to Cars 2). It's basically like pitting s comidian in front of a female drama and saying "grade this". It's gonna be opinionated.