The old one that people praise isn't that good. It does all the things it needs to, but it uses eight layers of popup dialogs, it works poorly at DPI's over 150% and so on and so forth. Basically, a 2005 Windows UI is mostly a
bad windows UI.
The proper solution would have been to refresh the old one. Make a full-featured control panel that uses just slightly more modern UI paradigms and technologies. And with zero weird extension points for third parties.
But no, instead we get half the controlpanel made into a usless minimalist web design look, and the other half is still the original.
I don't know what parts of the control panel must remain for backwards compatibility (with what!?) or why someone even thought it was a good idea to have extensibility points that become a nightmare of compatibility of maintenance. Or why it's apparently more work to rewrite a single control panel page than it is to ship a whole major release of Office. But more importantly, I don't care.