Earlier quoted context omitted.
A hidden swipe at evil/vim fans by an emacs author?
No, it's clearly just more sane. Without any knowledge of keyboard escape sequences, why should down come before up?
The existing mapping is ridiculous. A,D,J,L are all in a horizontal line, but are mapped to vertical motions.
There are many choices, but for example, using A/Z for left player up/down and J/M for right player up down would not require any mental work. Once you place your fingers, up is up and down is down.