Okay, I'm not a gun expert but what recreational civilian usage are you going to find for a sawn-off shotgun?
During a home invasion you'd love to have a weapon strong enough to stop someone with a single load of 00 buckshot, but small enough to easily maneuver through rooms and doorways (and a barrel a few inches shorter is a few inches better for CQB). Also any firearm is a nice 'surrender or get pwned' signal for the burgler.
A sawd off would also be easier to keep in your car if you think a .357 Colt Python doesn't look scary enough to solve a road rage incident with a really agressive opposition (let's say drunk and armed with a nice long baseball bat)
But I'm also not an expert. Any police officers here?
The fact that you think a firearm is a good way to resolve a road rage incident just scares the beejeezus out of me. For the record, no kind of firearm is a suitable way to solve any sort of road rage incident. The correct way is as follows: (1) drive away and (2) call the police. First off, there is no actual guarantee you're going to be able to get the weapon out of your car (and we're assuming here that you live in a jurisdiction in which that would be legal, which I would think is entirely moot to 90%+ of HLP anyway), and there is also no guarantee that they aren't going to be able to pull a firearm faster than you AND pull the trigger. Which is especially stupid over something like road rage. I've met lots of people who have handguns under their front seat in the States and without fail NONE of them could pull it out in any reasonable length of time (which is the time it takes for an adult to cross a distance of 25 feet to their window, or roughly 3 seconds from when said person starts running).
Onward...
The whole point in the ruling, kara, is to clarify that civilians may own firearms for personal defence outside of a militia role. Essentially, it clarifies the individual's right to bear arms for personal use without opening the floodgates to all kinds of ridiculous weapons and attempts to strike down existing controls on firearms.
Handguns and sawed-off shotguns exist entirely for personal defense. Granted, handguns can be used for target shooting too but there isn't much use for s short shotgun other than personal protection. Not something I'd think people would tote around in a vehicle by any stretch, but certainly a weapon suitable for carrying in tight spaces such as houses and requiring very little in the way of aim in order to be effective. It's not a recreational weapon. Hunting with one would be damn near impossible. To be fair, I suppose a sawed-off could be used for target shooting in a recreational setting if loaded with slugs instead of buckshot...
I'm not necessarily agreeing in principle with the ruling or the weapons use, just outlining possible ways in which they are.