I think the ability to fix it is key, yes it should "just work" but what about when it "just doesn't"? Being able to modify the OS, GUI or any part of my system

I think the ability to fix it is key, yes it should "just work" but what about when it "just doesn't"? Being able to modify the OS, GUI or any part of my system is useful. I'm more impressed by an OS that can run on any hardware than an OS that needs specific hardware. I use Mac, Linux and Windows but to me lack of choice in OS or ability to modify anything isn't a good feature or one to boast about.