Traditionally in 3D Zeldas, pressing the B button would slash the sword, thereby taking you out of any aim mode, etc.
Now, the "b" button functions are effectively handled by the wiimote.... and moving it around in aim mode just aims things.... would you just press A or something to get out of the aim mode?
And what about on horseback, where you'd want to be able to use the A button for the whole horse speed thing?