> a fully-featured File Explorer work-alike complete with previews of every file type and a full-on context menu copy

Corel LinuxOS did this at the turn of the century. Xandros took it even further.

Sadly, although a company is still around and owns the names, they do not use any of the original code.

Xandros's version of KDE 2 was the best Linux desktop of its era and it wasn't even close. By a decade later, Ubuntu Unity took that role, but a lot of people don't know how to drive Windows by keyboard, and aren't willing to learn new things, so they hated it -- especially here on HN, which called for it to be cancelled, and Canonical listened.