In reply to Justin Tadlock.

Thank you for your reactive response ;), I'm thinking of your first proposal instead : "Would a faux folder feature work? Maybe by creating a new taxonomy — let’s call it “media folder” — that allows users to group their media? If the only purpose is sorting via the admin, that could be a possibility. A taxonomy could give you all the benefits of sorting without any of the roadblocks of moving around the actual files."