Wait, how is the keyboard so much better? Either way, in FFXI or WoW, you're controling movement with the right hand and macros with the left.
In WoW you're moving with your left hand, doing macros with your left hand and mouse, and moving the mouse and camera with your right hand. You really wouldn't take your right hand off of the mouse mid battle to hit a macro with your right hand, right? The only reason you would do it is to type.
In FFXI your right hand is moving your character, controlling the camera, pressing macros, and typing all very smoothly, while your left hand is typing and hitting macros. In some situations it actually can become advantageous to criss cross your hands and switch them for better comfort and reaction time. (Hello standing in one spot and camping Hoo Mjuu the Torrent for hours <3)
There's a pretty big difference between the two. Trying to compare keyboard only in ffxi to keyboard only in WoW is like comparing.. let's just go with apples and bananas.