Wow! Some aspects of this thread got heated pretty quickly.
I'm going to try to keep politics out of my post and just provide some facts that may help the original poster in his/her question regarding why would someone want to own an assault style rifle.
Today, there are still legitimate uses for rifles. Not if you live in a big city like LA or NYC. But there are legit uses. I remember pulling into my in-laws house a couple of years ago. There was a skunk meandering along the back side of their 6 acres. A recent study up there found over 80% of the skunks in that area were infected with rabies. Not wanting a probably rabid skunk anywhere near my kids, I grabbed my .22 long rifle that I had brought up to sight in the new scope and he grabbed his .22 and away we went. With a new scope not sighted in, I had a very low chance of hitting it but we did get the skunk to leave the area rapidly. Many ranchers, farmers, and land owners use rifles to control for just such issues. You don't want a rabid critter near your horses or livestock. In Texas and other parts of the south, there is a massive problem with non-native wild boars that do a ton of damage to crops, fences, native plants, etc. Wild boars are big, tough, and mean. They will mess you up. So you want to take them out from as far away as you can, hence a rifle.
Ok, so I pointed out some legitimate uses for rifle beyond the basic hunting.
Let's look at the popularity of the AR style rifle. The AR style rifle was originally developed for the military. One of the design aspects of the AR style was the modular design and interchangeability of parts. It's a flexible platform that is easily customized to what you plan to use it for at a very reasonable price. Want to go wild boar hunting? You can set up the AR with a multi-piece scope system that allows you to have a long range scope for an open field distance shot. But there are scope systems that allow for that scope system to be rotated out of the way so you can use open sights or a short scope that is good for short range...as you might find if you were walking through woods in search of wild boar.
A scope that is good for long distance (100+ yards) is typically not good for close up shooting (25 yards or less). A good example is a friend of mine and I were squirrel hunting years ago. It really was just an excuse to go stomping through the woods in fall. Anyway, he had a squirrel run down the tree right next to him. His rifle was set up with a scope. But the squirrel was all of 5 feet from him. He missed because all he could see was brown blur through the scope and couldn't tell squirrel from tree. It's easy to set up an AR style rifle to be flexible for this situation.
The modular design of the AR platform allows for a very flexible system that accommodates a wide range of conditions. Way more flexibility than your typical hunting rifle. Another example is I have a rifle I have set up for deer hunting. It is intended and set up for longer distance hunting such as you would find in the Dakotas or out west where a close shot is 200+ yards away. That's not practical in the midwest where deer hunting shots are typically less than 100 yards. So I would need two different rifles for the two different hunting conditions. With the AR platform, a person would need just one rifle with a few attachments at less total $$ invested.
Another key part of the modular design for the AR platform is it is very easy to change the rifle to fit your body and shooting form. My arm length is different from my brother or my father. Shoulder stocks for the AR platform come in various lengths and also ones that are multi-adjustable. This allows you to adjust how the rifle fits to your shoulder on that given day. With traditional hunting rifles, it's like the old Ford Model T - you can get it in any color as long as what you want is the color black. For traditional hunting rifles, it's pretty much that model comes with that stock. If you need it shorter, grab a saw and start cutting on your brand new rifle. With the AR rifle, you can easily swap out the stock for one that fits you well or is adjustable so you can use it when wearing a t-shirt in summer, or all decked out in cold weather gear for 15 degree F hunting in fall. The adjustments are handy for adjusting to your shooting position: standing, sitting, prone, up-hill, down-hill, etc. Custom and flexible. Are you a left handed shooter? Good luck as almost all rifles are designed for a right handed shooter. The AR platform makes it easier to modify for a left hand shooter.
Another part of the modular design is they can be built in several different calibers, but still have parts that are fully interchangeable. Plus the look and feel of the rifle is the same. Not all hunting rifles are available in the caliber you want. Sometimes, you are choosing a hunting rifle because it fits you well and making a less than ideal decision on caliber because it's not available in your desired caliber. With the AR platform, if you want it in .308 caliber, not a problem. .22LR, no problem.
The AR platform also allows for various barrel lengths and different weighted components to adjust the balance and the weight of the rifle to fit your body and your specific use. Have a disability that makes it difficult to hold up a heavy traditional rifle with your left hand? No problem, an AR can be custom built with a light-weight short barrel and rails to fit your restrictions at a lower cost that a custom made traditional hunting rifle.
I could continue on, but I hope this gives you some insight into why the AR platform is popular. Parts are plentiful, easy to produce, and allows almost infinite customization.
I won't get into magazine capacity. But the fact remains, there are significant parts of our country where you could easily be out for a hike and startle an animal whose reaction is to go on the attack. A walking stick is just going to piss it off. You don't need an AR for walking through Central Park in NYC except at night in dark places but that leads to the question of why are you so stupid as to go walking in dark, hidden places late at night in Central Park. But I can tell you, when I got my ATV badly stuck 2 miles out in the woods in northern Minnesota, the sun was setting and I could hear the wolves howling...I REALLY was wishing I had brought a gun for the long hike out. That was a long, unpleasant hike out. Or that time in Idaho when I startled that mama bear...
