Must have feature for mainstream adoption.
An additional suggestion/workaround is to update the protocol to have a file similar to a master boot record. Have all the files in the same bucket unnamed or with ignored original names and add a standardized small directory file that contains all file names and directory structure. Then whenever a user renames or moves a file, have the client side app delete and reupload the directory file with the new information. Client side present the files as if they are in a directory structure with updated names as opposed to the reality of all original named files being in the same root bucket.