Auto-save is bad because it saves everything without user consent, even if you don't want the changes to be saved. For example, let us say that you open a photo and hit the rotate button so that the photo fits your screen better, then you close the file. In the past, that rotate operation was simply a viewing option and did not automatically result in your original photo from being overwritten. But now, the photo will be automatically saved (causing a loss in quality in the case of lossy-compressed file formats like JPG); if you don't want the file saved you are SOL...you have to go fishing for the original in order to rescue it.