Silicone is inexpensive and suitable for cookware that gets exposed to heat. I bet that sort of thing could survive an autoclave.
A generic touch screen with dynamic controls is cheaper than a larger custom made keyboard or physical controls. It's the same reason we end up with power inefficient IoT devices that could be made with very cheap and efficient microcontrollers, but developing for those requires expensive expertise, so we end up with huge powerful ARM cores because it's more general and easier to code.
The common factor in both of these issues is cost to manufacturer vs cost to user (power, safety etc).