An old dumb phone of mine had a mini trackball I found immensely useful. The firmware (proprietary) was total garbage, but moving between menus was a breeze. Having a trackball rather than a touch interface means that icons and text don't need to be larger to be hit by a finger; all the user does is move the trackball until the relevant object is focused or text highlighted, then use it. Voila, lots of space saved for actual information.