Wayland is architexturally better than X11. X11 was developed in a time where any serious application more powerfully than a terminal emulator would be running on another computer, and everything else has been hacked on top of that. There’s hardly any security restrictions for things like keyloggers and key stroke injection. It’s old and maintenance sucks for the people currently maintaining it.

After a couple of decades, people looked at what the rest was doing and thought perhaps the old mainframe model isn’t necessary anymore. Windows and macros don’t model their GUI after mainframes with dumb terminals that happen to be physically located within the same machine, so X stands alone in its design architecture.

I think everyone maintaining graphics code for Linux distros thinks X11 doesn’t cut it anymore. Importantly, the people writing GPU drivers don’t seem to want to be held back by the extensions built on top of X11 (while others dutifully maintain their old drivers). This is work only the companies making GPUs can afford, without it, the drivers will stop working. There’s probably also a reason Android took the Linux kernel but stripped it of X11 acceleration and developed its own GUI stack. Canonical tried to get rid of X years ago by developing Mir and a bunch of small projects tried to create an X12 of sorts, but neither took off. Almost everyone is now working on Wayland when it comes to alternatives.

There are people who don’t care. Some GUIs will always be X11 and they can use X11 as long as the drivers and tooling still support it. Most X11 programs have worked without modification for years through XWayland, and I expect future applications to still work fine through some kind of reverse that’ll turn Wayland programs into X11 programs.

The problem is, X11 doesn’t really work fine for modern usage.

It kinda falls apart with multiple monitors, especially when they require different scaling or refresh rates (or both), HDR support would be incredibly difficult to add, it’s buggy, it’s virtually impossible to maintain or add features. Often fixing a bug breaks things, because the bugs in it are so old that programs have actually been designed around them, or even to utilise them.

Now imagine trying to adapt X for use with VR/AR displays and all the differences in window management that’ll be required for that.

It’s a security nightmare. Any app can see what any other app is doing. That means that if you have a nefarious app, it can scrape any information on your screen, without even needing root privileges. Then there’s a load of other vulnerabilities.

The developers have moved to Wayland because X is structurally unfixable.