I understand they want to improve the servers by increasing them and the work that would be done to have to implement it is probably something they rather skip.

But honestly, I don't think having an extra function such as AFK kick being a bad idea, I get what people say about a macro, but it would mean the window would need to be active, so I imagine a lot of people wouldn't a) make the effort, b) as willing to leave the game open running full pelt on their hardware, at least now you can alt tab it its basically the same as it not running.