Haven't you seen the multitude of commercials showing starving kids/animals suffering? If you don't remember them, I think that proves the point as to how ineffective they were since they did exactly what you're suggesting and have been terribly ineffective.
If you do remember them, can you tell me if their videos went viral? Did anyone even LIKE any of them? Did you donate money to any of their causes? Almost certainly not. I, and everyone I've ever spoken to usually respond by wanting to change the channel in response to the horrible sense of guilt they gives. That's what the response is when similar groups take your suggestion.
Contrast that with this completely opposite approach you're disapproving of. It's created the most viral video ever, inspired the American people to know that we CAN influence our leaders, and created an unbelievable level of awareness toward a particular problem.
Those are just the facts. As for my opinion, I think that IF a video focused on the children could theoretically gain similar virility and awareness, then Kony would have been just as alert in response and created just as much of a "greater threat" in response as you're suggesting. Either way you're letting Kony know we're on to him and want him stopped.