Kids are kids but manners are manners too. There are appropriate places for kids to run and play...a buffet is not one of them. When they come to a point where they are banging into my stroller, thats a problem.
Letting a WALK around on an airplane for a few minutes is not a problem as flights can be long. I understand this. I don't understand why parents let their children run up and down airplane aisles though.