I should never have to provide a reason as to why I own something. But since you asked nicely I will give you a few reasons.
1. Self defense. In my case I am issued a AR by my dept (I’m a sherrifs deputy). I also have a AR in .300 blackout which is a great round and I will explain a few other uses for that caliber later. But I can use subsonic loads for self defense if I lived in an apartment or residential neighborhood. They fly slower and it takes a lot less to stop them. That means if I miss it won’t go through the wall and kill the neighbor. But I live in a rural area so I use supersonics because they carry more energy.
An AR is a low recoil rifle so it’s easier to shoot accurately in a stressful situation. Most ARs have adjustable stocks so they can fit anyone in the house weather it’s your 12 year old daughter who’s home alone when someone breaks in or it’s your 6’4” husband who is in the same situation.
2. Hunting. They make ARs in all kinds of calibers. Some rounds like .223 remington and .204 ruger are great for small game like coyote but there’s lots of calibers like .300 blackout, 6.8 SPC, 6.5 Grendel, .50 beowulf, .458 SOCOM, .308 Winchester and a whole bunch of other calibers are good for big game like deer, elk, wild boar, bear, and lots of lesser known animals.
Again an AR is a modular gun so you can set it up how you want it. You could get a rifle with a 10” barrel for wild boar. Or you could get a rifle with a 20” barrel and go after deer or elk.
You can also use different parts to make the gun weigh less so it’s easier to carry around all day.
ARs are the lego of the firearm world and you can make it meet your needs.
This is only a couple reasons and I’m running out of time to respond so I will leave it at this. Feel free to message me if you are in WA and I would be more than happy to let you shoot mine. I promise they aren’t scary.