Some people like moving the scroll bar (which seems to be your preference). Other people like moving the document (which is my preference). There's no right or

Some people like moving the scroll bar (which seems to be your preference). Other people like moving the document (which is my preference). There's no right or wrong choice here. The current default logically makes sense -- your cursor is located at a document, and when you're moving your fingers upward, the document also moves upward. But like any changed default, there are people who liked the previous setting. And there are of course people who want to use (or have to use) other OSes where this setting can't easily be changed. Those people can change the OS X setting at will.