It would be nice to have a config option to control a confirmation dialog before performing a drag and drop operation. There would ideally be two options: one that controls the dialog for folder moves and one that controls the dialog for file moves. When a folder or file is dragged/dropped, a dialog would ask the user to confirm his or her intentions.
While I can't consistently reproduce it, there are times where folders are accidentally dragged/dropped. This appears to occur most often when Assets is busy trying to load its thumbnails and you go to click a different folder. It's as if the first folder selection hasn't released yet, so Assets tries to drop it on the newly selected folder, things go crazy, and now there's an accidental drag/drop.