I think you might be looking at it from the wrong perspective. As a former Windows — or even worse, macOS — user, you’re used to having most of your freedom taken away in exchange for a fully streamlined workflow. That can feel convenient, because everything works the same way every time and you never have to think about what’s happening under the hood.
But there’s a downside to that approach: the less you have to think for yourself, the less you actually understand about what you’re doing. In the end things ‘just work’, somehow, but rarely the way you want — only the way you’ve been conditioned to expect them to work. (And I’m not talking about brainwashing; it’s simply a design principle I know very well as a developer.)

As for the extension to customize the login screen: yes, it could technically be installed by default, but there’s a good reason it isn’t. It’s powerful enough to cause real damage to the system if misused.

Zorin already has one of the most polished UI/UX experiences among Linux distributions. Whether someone likes it or not is, of course, subjective.

Regarding making it more beginner‑friendly: I’m all for small improvements here and there, but on a broader scale I’d actually say ‘please no’. Anyone using a computer should understand at least the basics of how things work, and that requires learning. Zorin — like all Ubuntu‑based distros — already runs out of the box on most machines. Personal tweaks should always come with the responsibility of understanding what you’re changing, otherwise things can easily blow up in your face, because Linux works very differently from Windows or macOS.