[RACooper]

It's a sad but unfortunate fact that people's interest in positive stories is limited... while negative news always sells.
Another point is that the negative news is more visually interesting than positive news (for the most point)... now when the visually grabbing news was positive during the begin of the War in Iraq, the news agencies couldn't get enough of it... but as the positive news became less visually interesting (expolsions, fires, combat, etc.) the negative news started to come to the fore, as it had the elements that made great newsclips.

So if the news is limited (time wise) in their broadcast schedule, they will focus on the story that will garner more attention.