Since we all agree that we'll most probably all be using Ubuntu MATE until the day that we die I think it only makes sense to make it as sexy as it can possibly be.
And what I mean by that is back then, when I thought that I would be using win2000 until my last breath, there was a neat third party copy utility that has stood up to the test of time and that still runs today.
And that application friends is called TeraCopy and you can find it here https://www.codesector.com/teracopy
So my point is: how about bogarting every possible (or not) features of this great utility and give even more reasons to the windoze lovers to jump ship over here?
Bottom line is: caja copy is great. But it could be greater. And I do not believe that we need to reinvent the wheel on copying files as the road has already been paved a long time ago.
Besides, I never heard anybody complain about TeraCopy in well over 2 decades so I think that it makes a great model to follow for this community to strengthen their grasp even more over desktops users and usage.
Cheers!