I was excited by this app and thought that finally I would be able to drag and drop any of my files from Windows PC to my iPad connected by USB into "On My iPad" folder. But I was unable to do it. So we cannot use our oversized 256 GB and now 512 GB iDevices as plain dumb Pen Drives? I read about everywhere and the descriptions at imore and other sites made me feel that this Files App is making simple things more difficult. Am I missing something?