Files and folders on your computer look and feel the same regardless of how much space on your hard drive they take up. Delete a 5-gigabyte file or a 5-kilobyte file with a simple click and drag of the mouse. Sure, one might take a little longer to delete than the other, but there's no change in effort on your part. In the real world, we know that's not true. Otherwise, shipping would probably be free for everything (or at least a flat rate). Jan Barth and Roman Grasy experiment with this idea with DataBot.
DataBot is a mouse that puts on the subtle brakes for larger files, so it feels heavier. There's also a "breathing" function that shows you how often a file is opened. The lid of the mouse sort of opens and closes more rapidly for more frequently used files.
See the mouse in action below.
Do you really want your mouse to have more friction as you move your files on your desktop? Probably not. The whole point of the computer is to get things done quicker, not slow you down. However, as another signal or a way to interact with data (in addition to the visual), this sort of physical feedback might be useful one day.