Here's the deal. As a non-law enforcement civilian, if you ever need to use a firearm, of any kind, it will be at handgun distances. Kind of difficult to successfully articulate why you were in imminent danger of death or great bodily harm when you popped Mr. Unsocial at 100yds. I'm not saying there will never be a circumstance like that where it is justifiable, but.....
So, why a shotgun or rifle? Power, accuracy, magazine capacity, control. And there are short and long pistol distances. The point is, a carbine or shotgun is hugely more effective than a handgun at handgun distances. For those reasons, they are desirable. Get training on all of them. But especially the pistol since you are unlikely to carry the long gun outside the house.