I've been half joking lately that if I wrote an OS, I'd call it Nostalgia OS. I'd aim for a UI reminiscent of windows 98 / windows 2000 / snow leopard. With HID guidelines and a rich, clear, cohesive set of UI widgets to build applications with. I think that was the peak computing user interface - at least as I experienced it.
Of course, the kernel would be based on capabilities (probably SeL4). And applications would probably ship as WASM bundles. And I'd have a built in local first user database built around CRDTs and things instead of a file system, kinda like a modern Lotus Notes. But for the UI? That era was great.
My favourite OSX in terms of visual design was the Panther/Tiger era personally. Leopard looked good, but there was something really cheerful and friendly about Tiger. The iPods of those days were also really well thought-out in my opinion.
Definitely a world apart from the utilitarian Windows 98 UI.
To some extent (not capabilities), Haiku fits the bill here (https://en.wikipedia.org/wiki/Haiku_%28operating_system%29). Applications are bundles (but not WASM of course). The UI is very clean. The whole OS is also elegant and very fast on modern hardware.
Yes because BeOS was way ahead of its time. A complete new OS, doing all system things so much more efficiently, that it could allow wasting cpu time on high level actions, like moving windows in real-time while they were playing videos.
On 1993s hardware, impossible with Windows or OS/2.
Of course, the kernel would be based on capabilities (probably SeL4). And applications would probably ship as WASM bundles. And I'd have a built in local first user database built around CRDTs and things instead of a file system, kinda like a modern Lotus Notes. But for the UI? That era was great.