I do not like local news or really any news on TV.
The best conversation I heard about this was from a sportscaster trying to explain the role of sports in our lives.
He said Bad News tends to be immediate things, murder, fires, plane crashes. And outside of Miracles on the Hudson, Good News tends to unfold slowly over time.
In our modern lives where we have instant access to everything, the media tends to gravitate towards the immediate story. Which end up being the most shocking, disturbing, or depressing.
He said that's why we love sports so much. It is an escape from the bad news into a world where you can experience the entire range of emotions. And even find villains to hate who aren't really that bad in the real world (like ARod).