The first rule of a gunfight is to have a gun. So, there’s a lot to be said for a gun that you have on your person and not left in your car, house, boat, etc.
I’ve always viewed handguns like parachutes – You hope you never need it, but if you need it, you need it RIGHT NOW and nothing else will do.
As for carrying a handgun for self-defense, we select handguns because it is impractical to carry a long gun while going about everyday life. If confronted with a potential deadly force situation, even law enforcement officers will equip themselves with a long gun if they have even the slightest opportunity to do so. That’s just good tactics. About the only time a handgun is superior is in very close quarters (think tunnel rats in Vietnam) or when you really need to be able to holster the gun to do something with both hands (like fight, access another weapon, hold onto a prisoner, etc.)
Guns are a PITA to carry all the time, even in an open carry holster. They are heavy, bulky, must be continuously protected and defended, and are generally a nuisance. So in order to have that gun and not leave it in your car, nightstand, safe, boat, etc., it needs to be something you can tolerate.