A handgun in the hands of law abiding citizens is a reactionary firearm. Concealable when out in public and easily accessable from the bedside ,either from the top of the nightstand or drawer. Rifle and Shotguns are not by nature in most civiian applications and one standing next to the bed can easily knocked over when someone reaching waking quickly from a sleep. Not to mention thier's a reason loaded longguns in most place leaned up against a vehicle is illegal. It's not a safe practice.
If time allows retrieving a shotgun is fine. What is practical and works in real time is different than most of the armchair rambo crowd think works.