Would or already is? You said "they already have" one alternative attack to Thrust. Moreover, pressing alt, left mouse button and aiming at your enemy and most likely moving your mouse as well as moving my char by pressing WASD is already taxing enough on my brain while fighting, adding one more key that would be necessary to perform an attack would simply make me not use it and go for less complex and more reliable ones. If you feel like having to press 4-5 keys to perform a single attack which might fail instead of giving a good old right to left swing which always makes their blood gush out of their armor, be my guest.Another keypress and attack would make the character bash/shove/pommel-strike or whatever.
There is a certain limiit, a threshold to how complex the controls should be, there is also a limit to how many things at once I am willing to press and think about while playing. 4-5 key keyboard and mouse combo is nonsense.