Because if "working" was the only thing people ever wanted, we would be using Windows 95 or something. People want "not crap", and everything related to X11/Xorg is a gigantic pile of crap.
> terminal latency of Wayland default compositor vs X
I'm not sure what you mean by "default compositor" — Weston? — and what's "X" — Xorg without any compositor, with the Windows 95-esque situation of everything drawing into one buffer?
Yeah, you can decrease latency by a tiny bit by not compositing at all, but the result is totally unacceptable visually. People generally don't want to look at Windows 95 anymore.
And this is the issue with Wayland vs X11 when it comes to compositing: Wayland forces it down your throat, either you like it or not, whereas X11 enables it but doesn't mandate it so if you dislike it you just don't use it.
(though this isn't the only problem Wayland has... and FWIW Windows 95 is in many fronts superior to any desktop you can find on Linux)
Most users want a UI from $CURRENT_YEAR, not one that makes them think of Spice Girls songs and AOL Instant Messenger.
> Wayland forces it down your throat, either you like it or not, whereas X11 enables it but doesn't mandate it so if you dislike it you just don't use it.
X11 is architecturally ill suited to a compositing environment. Inasmuch as compositing solutions exist, they are janky hacks that introduce more processes, more context switches on the hot path, and more latency than Wayland, which was based on $CURRENT_DECADE graphical principles from the ground up.
Sometimes you can't square the circle and engineer a general solution. Sometimes you have to engineer for the common case only. For desktop usage, the common case is "user who is used to Windows or macOS and does not want to regress backward in terms of UI". For such users, a noncomposited Windows 9x-like desktop is unacceptable. A broken, laggy, hard-to-maintain pile of hacks is also unacceptable. Wayland solves both those problems, which is why virtually ALL of the hackers working on the Linux graphics stack have jumped ship from X to Wayland. Like it or not, you will eventually be using Wayland too.
> Most users want a UI from $CURRENT_YEAR, not one that makes them think of Spice Girls songs and AOL Instant Messenger.
This is rather incorrect assumption. UIs is not something people want, it's something people want to not to get in their way, i.e. the opposite of wanting. And to your example modern Gnome is actually worse than AOL times UIs, it breaks a lot of expectations users used to Mac or Windows have, with proper menus not hidden away and better workflows.
Your priorities are wrong. Latency is the most important metric for doing actual work. This means that the windowing system should allow clients to blurt out pixels whenever they want no matter where the current scanline is positioned.
Apparently there are patches on the way [1] that try to mitigate the severe design flaws of wayland in that regard. If wayland will ever reach X11-like performance remains to be seen. Right now this is not the case.
Partial update is not an improvement for latency in the way you're thinking about it. It's mostly an optimization for tillers so they don't have to rerender some parts.
You seem to broadly misunderstand several parts of the modern display architecture -- the goal you insist any sane window system should provide hasn't been provided by any, including the X Window System.
> terminal latency of Wayland default compositor vs X
I'm not sure what you mean by "default compositor" — Weston? — and what's "X" — Xorg without any compositor, with the Windows 95-esque situation of everything drawing into one buffer?
Yeah, you can decrease latency by a tiny bit by not compositing at all, but the result is totally unacceptable visually. People generally don't want to look at Windows 95 anymore.