I have found out the reason for the scrolling being reversed is because Apple wanted the touch gestures to be more like iOS. When you're using an iPhone or iPad, you move your finger down to scroll up and flick up to scroll down. If there was ever a touchscreen iMac, I would want it this way myself but it does feel very strange using the Magic Mouse in the same fashion.
You CAN take it off, however, in the mouse settings.
You CAN take it off, however, in the mouse settings.