Kids travel, parents have a responsibility to keep them under their care. But, like the guy who works in Fort Mac and was flying from YEG to YQR 2 weeks ago so drunk/rude/loud/crass/afraid to fly, sometimes they can't always control them. What matters is that they are trying. Give them he'll if they kick other people's seats, do everything you can to try to calm a crying baby/toddler. Others will appreciate it.
By the way, our 5 and 3 year old slept while the loudmouth yelled immediately behind us. And as for the lounge, we tried both YVR and YEG on that trip. As soon as the kids didn't behave, we bolted. There is a difference between what you could do, and what you should do...