I handle my cameras outdoor in below freezing temp, several months of the year. A touch screen would be a real PITA for that use. I would rather vote for bigger buttons.
But if, as someone earlier in the thread pointed out, we could customize it, get efficient sliders and limit the functions to those we use, it could be a nice add-on feature. A bigger screen would defenitely be most welcome, to compensate for my deteriorating eyesight
5DIII, 1DX, 7DII, 8-15/4L, 16-35 f4L IS, 24-70/2.8L II, 70-200/2.8L IS II, 200-400/4L IS 1.4x, Zeiss 15/2.8, 17/4L TS-E, 24/3.5L TS-E II, Zeiss 35/1.4, Zeiss Otus 55/1.4, Zeiss Otus 85/1.4, 100/2.8L IS Macro, Zeiss 135/2, 600/4L IS II