And variable refresh rate, better fractional scaling (and per-monitor scaling), atomic updates, native touch & gestures. And the isolation/sandboxing is important. The problem is Wayland didn't have portals in the beginning (hence the screenshot issue).

Wayland isn't the problem. The pace at which distros (and GNOME, lets be real who is behind the push here) started stripping out X11 was too fast, and too early.