It also runs counter to scroll wheels on mice, which has a physical reason for the direction too.
One finger drags the cursor up and down
Two finger drags the underlying page up and down
Four finger drags the underlying space left, right, up or down
Perfectly consistent, no? I won't argue that forcing people to relearn scrolling is an uphill battle. But I'm a Dvorak typist.
- Page Up scrolls the page down
- Up arrow (eventually) scrolls the page down, too.
Looking at it that way, the only exception is be single finger drag. I guess that 'has' to be that way because otherwise dragging a finger down a bit would be too different from lifting it shortly, then clicking a bit down.