News runs 24 hours and need stuff to fill the time. It also needs to be short and snappy to cope with limited attention spans.
Do I think the world is a more dangerous place today? No. Simple. I'm in my extremely late thirties (thirty thirteen to be exact) and originate from Wigan. I can remember running battles every Sunday night in Wigan town centre. Coming out of the Banshee in Manchester on a Saturday night I remember seeing fights all down Oxford Road. The eighties were a great time if you're a fan of nuclear standoff between two super-powers. Again, media hyping up the threat of Armageddon. As TJ says, murder rate in the UK is down however murder and violent crime fills the airwaves because they need the ratings. I remember in the mid eighties there was a spate of vicious attacks on pensioners in their own homes, one was murdered. This happened in Standish, it made the regional news. It didn't get national coverage although I think it would now.
Bit of a ramble down memory lane, so to summarise; do we live in a more violent world? I don't think so. Does the news media whip stuff up into a frenzy with the net result that some folks live in fear? Undoubtably yes.