That's disregard for backwards compatibility to me.
edit: which is not to shit on wayland itself, it's to complain about the general attitude which is like "just don't do that" or "oh that's old, we don't support that"
I've actually used waypipe more often in the last year than I ever used ssh -X, thanks to a shift towards WFH :P It's sometimes useful to be able to run Firefox remotely from my workstation at the office.
It's supposed to fail hard. That isnt just a security hole in X, it's a total lack of security. The notion that any app should be able to monitor or manipulate any other app is archaic and wrong from a security perspective.
That "security" is useless on a Desktop where you run all programs as the same user. If you want a platform to run locked down "apps" that's fine, just don't expect others to be happy with the cost of that "security" when it provides no benefit for them.
Wayland compositors provide backwards compatibility with most X11 apps via XWayland, I don't think it's fair to say that they completely disregard compatibility