Well, even adding a touch screen still requires a redesign of applications. Buttons need to be larger, interfaces need to be designed for touch screen. macOS isn't targeted towards that (yet, I feel Apple's anti-PC touchscreen statements are too strong as it's an inevitable development). Consequently, the interface would be, alien. I've used Windows tablets (Windows 7), with a pen input device. It works, but it's awkward. Even if they'd had an iPad-quality capacitive input for fingers, with non-touch screen apps it would still be awkward. That's the same experience I'd anticipate using a touch screen with today's macOS and apps.

They need to layout a roadmap for this development, rather than dropping the hardware in without the software to support it. Chicken and egg problem.