It is all about perception and availability of information. Society is NOT getting more violent. We do however have an increasing population, so an absolute increase in incidents, however not a relative one. News travels faster, with mobile phones and internet, incidents you would not have heard of 10 years ago are suddenly within reach. If anything, societies are less violent in the last century. Try to get your hands on a 19th century newspaper and read about all the scumbags of the time. There will always be a percentage of people up to no good.
Deterrence has never been a good solution, as there has never been a connection between high penalties/death sentance and crime rate, in contrary, it seems to have a positive correlation!
A lot of crimes are not premeditated and therefore severity of penalty has no influence whatsoever.