Often it doesn't, but to me, that's not the point. The point is the consistency between disparate apps from different vendors and backgrounds is what matters f

Often it doesn't, but to me, that's not the point. The point is the consistency between disparate apps from different vendors and backgrounds is what matters for usability. That ability to know your way around nearly every app on first use, just from knowing the OS trumps most else. There's lots of things I use occasionally - I don't want to RTFM every time. I dislike how Windows and Android do a lot of things, and how OSX does some. I'd still prefer devs respect that than "improve" on it. When I find a utility to add a dark theme or fix some niggle the OS does really badly - multi-screen perhaps, the standard stuff interoperates with it just fine. The clever "knowing best" program is the one that breaks it, or interoperates only partially. eg Photoshop has a lovely dark GUI now, but now doesn't get the multiscreen util's extra icons. Let the user decide. They can add a multi-screen util or theme, or even simple things like xmouse and they should work everywhere, or they can just use the vanilla OS as they prefer. EDIT: caseysoftware puts it rather more succinctly.