There are many reasons. No one feels as safe as they did several years ago. Criminal acts seem more violent today. Simple auto thefts have become carjackings. The bad guys carry guns, the good guys don't.
Shootings occur over a wrong turn in a residential district.
Home-invasion robberies make the nightly news. In short, innocent people are having their lives turned upside down, and we see it every night on the news. People now realize that government cannot always take care of them. There seems to be a growing realization that the individual is ultimately responsible for their own well-being. Our laws have always recognized the individual right to self-defense.