Even with the fact that its using drag and drop, I dont see why that would impose the requirement of using a temporary folder
I am also wondering about this...
This was explained too many times in the forum already. Shortly: Windows drag&drop mechanics does not allow source application of drag&drop operation to find out easily where the files are dropped. It is up to target application (Windows Explorer usually) to transfer files to destination. It is rather reasonable, because source application can hardly transfer files to all possible destinations. Keep in mind that you can drop files not only to directory, but even to ZIP file (or any other archive), remote directory (via FTP, SCP, SFTP....), trash, ....