Re: "were made available for other OS" @ defiler
The average person will wonder why one application looks so weird next to the others.
As opposed to Windows 10, where the application could have any one of three "design languages" in play, be they desktop/Win32, UWP, or UWP+Acrylic?
I see just as many Windows applications reinventing the wheel and using their own design widgets than I do in Linux, and ever since Windows 8, it's been a half and half OS in terms of UI, and now Windows 10 has a third entry grafted on top of that (Acrylic).
If you use one of the GNOME-derived desktops, it's actually more consistent than in Windows (in my experience at least), as applications using GTK+ (the most common kind) integrate seamlessly. If you use KDE, it's a mix of native Qt stuff (and Qt versions of things where available), and GNOME, with its ass-backwards buttons on everything.
Any arguments about UI superiority in Windows became irrelevant post Windows 7, I think. If Windows 7 was still representative of the direction Windows was going, I probably would still be using Windows myself. Windows 10, however, is unusable, and is unfit for any purpose by design.