So to some extent, does doing this better at the scale of a modern user-facing OS provide enough return on investment?
(P.S. - Latest Windows when installed with MS 'PowerToys' brings a few missing things in Windows from macOS where it might otherwise shine)
Some people seem to hate it but for me it’s absolute joy to use and the only file manager designed properly and for power users.
Explorer totally falls apart once files in a folder are in the 10,000s performance anside its sorting and search are anemic compared to Finder.
The "document-oriented" window management and the fact that you can Cmd+X selected text, but not selected files is deeply bizarre.
For a declaration of my own bias, as a kid I was put in front of macs, so it impressed me during important years (8-15 years old). I don't use any macs nowadays. I use file-cutting-enabled linux systems.
With this background I don't see that opening files or folders with the return key as intuitive at all, I don't see the connection. It's not a bad idea, just an arbitrary choice like others. Command+O I can understand too, O is for Open and on the mac they decided to introduce (i.e. invent and teach the user) a universal action open that works the same for files and programs (no separate open vs execute). That's a positive example of consistency, at least.
Enter for rename is perfectly sensible to me. Personally, I use it more than Cmd+Down to open files.
The Cmd+C + Cmd+Shift+V paradigm for cut/paste makes just as much sense as the Windows paradigm. Either way it's a just copy and delete function. Would you rather choose to delete at the time of the "paste" or at the "copy?" I don't see a clear reason to prefer one over the other.
This means that even the little-seen parts of the OS that have never been redesigned (like DigitalColor Meter, the Bluetooth file receive dialog, ColorSync Utility, Keychain Assistant) still look pretty much at-home in the latest design.