I think one of the most harmful elements in our society today is the 24 hour news cycle. The stations that report news 24/7 have to search long and hard for items to fill the hours. So a lot of news stories are repeated over and over again.
You are right it does give a person the impression that our world is all bad and that there is little good. I guess good news does not sell advertising so they go for what is shocking and sensational.
I don't mind print media as much because you can pick and choose what to read but the news on TV is horrible, you are being bombarded by sight and hearing and it is just too much.