They aim at bettering the Linux user experience across the desktop by (it sounds like) unifying the platforms.
Not going to happen.
I’m in disagreement with you about the “freedom” thing being a drawback for a variety of reasons. Despite Windows having Java, GTK, Qt and all the other apps, it hasn’t stopped Windows from being popular.
Lack of options isn’t what made Windows a better development target for mainstream audiences; ABI stability is. DirectX + Win32 API gave developers a sane set of things they could target for their apps once and have it work for years and years, and that gave Windows killer apps.
Many of the apps written in the heyday of Windows XP still run fine on Windows. The most serious porting effort needed was the move to x86_64, not refactoring for API changes.
Linux hasn’t had that (and still has a way to go), because until fairly recently, “Linux” hasn’t had a direction. For better or worse, now it does.
Gnome, GTK, Wayland+Vulkan, Pulseaudio, and Systemd is “Linux”. It’s the only set of software designed explicitly for Linux, everybody else be dammed. Other things might work, but none of them are “Designed For Linux”.
KDE runs on Windows, it runs on Illumos and FreeBSD, and it runs on Linux by virtue of being a “cross-platform, Free Software desktop environment”. They’re aiming to do that, not “be the best Linux desktop experience”.
But the real reason is because many of the companies involved have invested a ton of money and developer time into their flavors of choice. Suse and KDE are so intermingled at this point that asking Suse to drop KDE is effectively telling them to drop their branding efforts. Being “not RHEL” is a major selling point for Suse.
Curious to see what comes out of this gathering, though. Suse does good work when they set goals and work with other distros to accomplish them. The Reproducable Builds effort is fantastic.