It's not just about replicating this functionality. It's about having an open framework that makes building these tools, and other unforeseen tools, easy. X11 was very accommodating of this.
For example, I like to run xsnow during the holidays. Wayland's answer to xsnow is -- we don't support that, but tell you what, draw up an RFC for a D-Bus API for desktop snow and wait 5-7 years for compositor implementors to consider incorporating it. Or something completely different. You know, whatever. It's like you have to prove your use case is valid to the community before you can even start hacking on it in a way that you can expect it to work with more than one DE.
For Wayland the attitude is "Fuck you. You get a buffer for a desktop window and that's it. [Wayland does not support nested windows.] Oh, that's not enough? You're not writing a desktop app? You want snow on the desktop/a desktop magnifier/a hall of mirrors effect toy/an anime window sitter/pinnable menus/something that responds to global hotkeys/etc.? I'm sorry, did we not anticipate your pwecious widdle use case? Fuck you. No one actually writes applications that way any more, nerd. Go back to the nerd table. We're trying to get the cool popular Mac-using kids to notice us here."
The X11 security issues are mitigatable with some changes to the server implementation. The Wayland approach really never was about security. It's about letting the cool kids define the shape of the Linux desktop to the exclusion of ordinary users/hackers.