I certainly don't condone anyone breaking their rules of engagement, but as your link makes clear, the majority of these "children" were 16/17 and throwing rocks, Molotovs or "fireworks" at the time, so it's already an edge case for use of force, and I strongly suspect that Hamas uses these events as cover for more lethal attacks such as every child's favourite, the fragmentation grenade.
So factor in that you're mostly talking about relatively poorly trained conscripts, not much more than a year or two older than these "children", and you're asking for mistakes to be made, which of course is a world away from the deliberate murder of 600 civilians in one day.