As noted by me above, most laptops lack a numpad. That means that the arrows would need to be enabled for movement as well. It works awesomely in the alpha version, and it's a common mechanism for movement in most any game, so why it isn't in the beta client I have no clue.
Not having to bother with the mouse would make this a very much more enjoyable game (it'd be one of only a small number of games that wouldn't require a mouse to work, something I consider a godsend).