it’s seems quite annoying to have another remote
It totally depends on what you do with your devices. On my main TV, I have game consoles, Bluray player, and an expensive soundbar, each with their own remote, but all of my remotes stay inside my TV stand cabinet with the exception of my Siri Remote. The Siri Remote is used 99.9% of the time with my set up. It automatically controls my soundbar volume, and turns my soundbar and TV on and off.
what function dos the Apple TV provide thats not already included in Apple TV app that is loaded on the various Apple OS’s? - and even run’s on some of the smart TV OS’s out there??
Apple does a really crappy job explaining the benefits of the Apple TV, and if they spent even a fraction of the time and advertising on the Apple TV as they do with ATV+, I think more people would use it.
First, there is a lot more to the Apple TV and tvOS than the Apple TV App. Actually, I don't even use the Apple TV App, and have the "TV Button" on the Siri Remote go to my home screen instead of the TV App.
There are apps on tvOS that are not on other platforms, so that alone might be a reason to go with an ATV. One of my favorite apps is Coubicle TV. That isn't on any other platform AFAIK.
Updated apps and OS. Some Smart TVs are known to have only a couple years of updates of their apps. The most common apps on the ATV are still getting updates since the launch of tvOS in 2015.
I used my ATV as a hub for HomeKit. I think you can also use HomePods as a hub as well.
Casual games, and not just Apple Arcade. The majority of gaming I do now is on the ATV. They are very casual games, but still fun. The HW is capable of modern AAA games, I am sure Apple could make the ATV more of a gaming device if they wanted.
The ATV travels with me. When I go on a trip, I take my ATVs with me for overnight stays. Try to do that with your TV, I am sure one could, but it doesn't travel as well.
Integration with other Apple devices. While most modern TVs can connect to iPhones via an app, the Apple TV has everything built into it. You can also control your ATV via an Apple Watch, which is helpful to quickly pause a show I am watching if I am away from the remote. AirPods connect easily and quickly. Setting up a new ATV with super easy with an iPhone, and involves very little effort from the user.
This goes along with the last one, but you can easily calibrate the color of your display that the ATV is connected to using an iPhone's camera and the tvOS Color Calibration tool.
That is just a few things.
Now with that said, I can completely understand why someone wouldn't think the Apple TV is worth the expensive price tag especially since Apple doesn't ever advertise the Apple TV and show why it is such a great device.
Even if Apple did advertise it more, I still think many would choose cheaper devices like a FireStick or the built in apps of a Smart TV versus the ATV if they just plan on using it for streaming.
The ATV is capable of being much more than just a streaming device, but due to many things Apple has done (or not done) with the platform, that is what most people associate it with, just an overpowered, but overpriced streaming box.