I don't have anything against using the mouse, as long as it doesn't break the gameplay. Imagine a player controlling one of our characters using the keyboard, and then having to grab the mouse in order to quickly use a potion that will help it avoid / trap / destroy an enemy. My goal is to make sure that the gameplay isn't fragmented, even if this means to make the player use the mouse at all times or make sure that the potions are only used in areas that aren't dangerous for the players.