Very much this. It's all about being organised as a parent (you have to do your best to ensure they are not going to be too bored, and being prepared to discipline your child. I find it far FAR more annoying seeing a kid get away with shite anti social behaviour than a kid crying for a short while because his parents have told him/her off for good reason.I blame the parents - the kids are bored, hungry or tired and the parents just don't seem to be in control of things.
I have taken cloud junior on many flights, longhaul and shorthaul, and he hasn't cried once. He also knows he's not allowed to kick the seat in front.
But it's always a grey area. I remember flying to LA and the two year toddler on the other side of the aisle was having his bottom WHACKED every time he stood up in the chair. The boy was actually being very sweet and not irritating anyone, the parents were physically absusing him and hadn't brought him a SINGLE toy to play with. I complained to the staff, and so it turned out did several others. The stewards ended up reporting him to social services.