Certain allowances have to be made for kids or at least some level of tolerance and understanding. If one gets in my way walking through a shopping centre it annoys me but its understandable because they haven't developed adult self awareness skills. If an adult gets in my way its far more infuriating. Even the best parents however can't turn their kids into functioning robots. As far as planes are concerned it would be common sense to have a seating areas for parents and children and another for grumpy old men like Al and Theno. Maybe more people should take up the issue with them. Even then what can you do if some gigantic fat guy ends up being seated next to you? That's even worse.
If they start screaming on a plane that's what headphones are for isn't it? Can understand if you're trying to sleep but that's far from ideal on a plane anyway unless you're in top class.