Why wouldn't there just be a small trackball on the nose, wouldn't that be more practical?
Because you'd be constantly changing your volume up and down slightly while scrolling.
For navigating a great big thing that benefits from two axis scrolling? Yes. For literally anything else a scroll wheel might be used for, like swapping weapons in games? No. The clickyness of the average scroll wheel is actually pretty useful and can't really be applied to a trackball.
Why wouldn't there just be a small trackball on the nose, wouldn't that be more practical?
Because you'd be constantly changing your volume up and down slightly while scrolling.
For navigating a great big thing that benefits from two axis scrolling? Yes. For literally anything else a scroll wheel might be used for, like swapping weapons in games? No. The clickyness of the average scroll wheel is actually pretty useful and can't really be applied to a trackball.