Earlier quoted context omitted.
What exact type of input is being grabbed by these screens? "Critical pilot systems"? Touchscreens already exist in airliners, for systems used by crew and passengers, but that's beside the point.
I fly recreationally and all the higher end gear has touch screens. Some of them are redundant with paths using hardware controls or not. But that's definitely the minority. There are a slew of critical operations that I simply cannot complete without interacting with a touch screen. Not saying it's right or wrong but your original post is 100% incorrect.
Many recreational pilots fly with uncertified gear (GPS in particular), and even regular smartphone/tablet apps. They also have the required paper documentation and certified instrument but that's just to cover themselves, and as a backup.