I'll answer the question with a question: If you have, say, 30,000 photos all stored in iPhoto, and you want to remove all those 30,000 photos out of iPhoto into normal folders such as you have in Finder. Sure, you can drag and drop each photo, but how do you do that for 30,000 photos? Say you're sick of Apple, and want to switch to Microsoft (just for argument's sake, not trolling), how do you do that?