Being the goal not "to win" for one of us, but to find (eventually) the best solution (both of us). It's actually cooperation.
That's how I see it also. I never liked wrestling.
...
you think a user whom you gave delete and upload permissions may be corrupted (morally) by the "move" button, or just it may tempt him at resorting things at his own taste?
No, I let the corruption -moral or otherwise-, to politicians and other crooks.
It's just problematic when into the VFS, some folders are shared among multiple users, with for all, permissions for upload and delete (and thereby the permission to move items) on these folders... when one or two selected users are allowed to move items, the administrator can follow the story ... if all can do it ... that's an another story!
But there's the same dilemma, some extent, with the "comment" feature ... is this the last user who writes a comment that made the best comment?
That is why treating certain options as "particular options" (via the use of groups), seems more practical than treat them as unavoidable subfeature of, upload, delete, etc. ...
Edit:
I sought for broaden the debate
, if I could find drawbacks with my suggestion, and I found two that we can evaluate as minor or major, depending of points of view:
1 - This will require additional settings to administrators (for include users in the choosed group)
2 - Use a template that includes this group for benefit from the new way to handle this function
(the "old way" still remains valid with the "old" template)
The fact that we are talking about beta versions, relativize, in my opinion, the "concern" to the second point ... Indeed, changes in templates seem more normal and natural when we refer to these versions.
As for usage security, I think this adds more security rather than to diminish it.