kain_kusanagi on 16 December 2012
If they added capacitance it would just as underused or even more underused as the Wii Motion Plus. Devs don't want to spend the money to support two separate input types.
For 3rd party devs the touch screen is going to very quickly become the "Menu Screen". It will be used for inventory, options, etc. and little else. Nintendo has no incentive to increase the manufacturing cost for something that would add so little to the console. At least the Wii Motion Plus added better motion controls, but so few games used it it almost wasn't needed. As a Zelda fan I'm glad I have Motion Plus for Skyward Sword so the motion controls wouldn't be as bad as Twilight Princess, but really I would have rather both games used standard controls.
