We now understand that a program that can secretly take screenshots at will can spy on all your conversations and steal your credit card number. That isn't quite as bad as root, but, honestly, for most users it's pretty close.
Wayland is absolutely doing the sensible, conservative thing when it comes to screenshots.
No, I'm pretty sure that was always understood. What Wayland is doing -- breaking expected desktop functionality -- is not sensible at all. Window's permission model is more sensible as it actually accomplishes something.
Wayland's "fix" isn't one because on the vast, vast majority of systems any compromised program running under your uid can begin debugging another under your uid, completely circumventing any permission system Wayland tries to create. Have a root terminal logged in, or maybe open one later? Any program under your account now has root if it tries hard enough.
People started freaking out about the completely normal and expected things you could do under X11 and kneejerked themselves into the current Wayland. Maybe it will eventually be relaxed. If it isn't, I can't expected it to replace X11.
Wayland is absolutely doing the sensible, conservative thing when it comes to screenshots.