My thinking, and the more trained individuals like KG and Sagebrush can correct me, is that handguns are primarily offensive weapons - concealable, easily transported, and used quickly.
This is not to say a handgun can't be used for defensive purposes, We all know it can.
The shotgun is a primarily a defensive weapon, able to toss out a lot of lead from a fixed position into short range targets. This isn't to say it can't be used in an offensive way, as we all know it can.
I also like the shotgun because I can protect the girls in my chicken ranch without shooting up the houses across the way.
