I've traveled with infants, a lapchild, toddlers and now a teenager, so I've seen it all. Sure babies will cry, and kids get bored, but that doesn't excuse kicking seats and acting out. Even 18 month olds have a lot of control over their actions.

They have removed children from flights because they were disruptive. It's rare, but it is an option. I don't hate children. In fact, I find them quite tasty when marinated with a soy/garlic glaze.