Shotguns do not need to be aimed. The general guideline is that buckshot spreads at about an inch per yard of travel. So at realistic home defense type ranges you are looking at a fist to open hand sized pattern. It cuts you a bit of slack over a single round but you can still definitely miss.
Shot penetrates walls less than other rounds so it is better for home defense. This has been demonstrated false at a variety of places including Box of Truth. Bird Shot does penetrate a bit less however it is designed to kill little birds and thus falls short in terms of deer/ man sized animals.
Shotguns are easy to use. This is confusing for a couple reasons. We lack standardization of what constitutes being capable of using a weapon (example: load, cycle, unload, score X in under Y time on El Presidente (or whatever), reduce stoppage, field strip and clean). Without that standardization we cannot say with validity that it is easier to learn to use a shotgun than a rifle. When the issue is dug into folks far too often have the impression that you can can load a shotgun, pump it and pull the trigger you are good to go. Sadly this is just not the case.
More to the point shotguns in an anti personnel role are not ideal and require a lot of manipulation. Most common shotguns must be manipulated before every shot and are reloaded 1 round at a time. This is especially problematic because they hold 5-8 shots. The more a shooter must manipulate a weapon the more chances they have to mess up and make the darn thing not work. In particular for shotguns short choking is an issue.
Now that the myths are set aside we can talk about the shotguns advantages.
Cheap. You can get new Remington 870's and Mossberg 500's for somewhere in the mid- low $300 range. Used guns can be purchased for less depending on their condition as well as how desperate the seller and buyer are. At that price range a solidly decent pump shotgun is something any functional adult can easily purchase with a little bit of planning. For a quality gun that will last you a lifetime this is a bargain.
Legal pretty much everywhere. If you can own guns you can have a shotgun. To the best of my knowledge you can have a pump shotgun anywhere in America. They are also looked at much more favorably abroad if that is a concern for you.
Versatile. Shotguns can harvest all manner of game, defend your home and be used for a variety of recreational pursuits. A Remington 870 or Mossberg 500 with a long choked barrel and a short riot barrel can do a lot of things.
Super Common. If a place sells ammo they have 12 gauge shells and probably 20 gauge also. For the common guns (Rem 870/ Moss 500) there is a ton of aftermarket support in terms of different parts.
To be fair shotguns also have some downsides.
Round count. More shots are better and shotguns fall short here. Between 5 and 9 rounds in most common configurations.
High recoil. Shotguns recoil more than any standard defensive type rifle. More recoil means a longer time between shots.
Slow Reloads. One round at a time in a rather cumbersome fashion. This makes the low round count all the more problematic because you need to be constantly reloading to keep from running empty.
Limited envelope of performance. Shotguns are very lethal up close but if you get past 40 yards (and that is generous) for buck and 100ish for slugs in a standard configuration they aren't much good. Yes rifled barrels with scopes are available that push this envelope but those only exist because of states that only allow shotguns for hunting. If you want this configuration just buy a rifle.
Mediocrity. As we talked above it is true that shotguns can do a lot of things. However like any 'jack of all trades' they are pretty mediocre at all of them.
Bulky/ Heavy ammo. Shotgun shells are big and heavy which means you either carry less of them, less of something else or pack a heavier load.
It is true that more purpose built semi automatic shotguns like the Benelli's and in particular the mag fed Siaga 12 have leveled some of the historic weaknesses of pump shotguns. These are problematic because the high price point cancels out one of the biggest advantages of the shotgun. Even beyond cost these shotguns are are in my opinion still a distant second to a rifle. Like we discussed some time ago I cannot think of a 2 legged predator situation where I would reach into a safe/ closet that held an AR/ AK and a shotgun and pick the shotgun over the rifle.
Anyway those are my .02 cents on that. Guess we can file this under the biannual rehashing of topics. Comments may be fun.