2nd Amendment Advocates of Tendo City

[Weltall]

you can protect your home just as well with a riffle

Sure you can. Assuming that you spot him from 200 yards away.

That aside, handguns are optimal for home security. Unless you're packing some kind of hand cannon, a normal handgun gives an experienced user the option of shooting to wound or disable. Using a rifle or shotgun typically gives you the options of "kill" or "mutilate", and neither are useful in close quarters--rifles especially are a liability here because of their size. Having to wield a weapon which might be as much as five feet long is not what you want to be doing if you're indoors.