This is just a cursor but I sometimes use the mouse, and I know you do too: this default 3D alpha-blended clumsily shadowed cursor is just uncomfortable.
I think the default cursor should be simple and _viewable_ on any display: this include being well contrasted and big enough. If the shadow should become an absolute necessity, then it would better not be so far away from the cursor.
First time users and newbies could be disappointed, if not upset: the cursor is the first thing they'll use. But, of course, they want to customize. Well, that's another problem!