Maybe that's the distinction - if you are making a product that needs to do exactly one thing (or category of things), it should not have a touchscreen, it shou

Maybe that's the distinction - if you are making a product that needs to do exactly one thing (or category of things), it should not have a touchscreen, it should have a button and a dial (eg toaster, oven, hob, clock). If you cannot map all common uses of the product to a single button press and instead rely on context, a touchscreen might be the better option