The highest quality display a lot of people have is on their phone, which has touch capability. The OLED MacBook Pro is rumored to use on-cell touch technology, meaning the display layer would be one and the same instead of two layers (which can reduce light transmission a little). That said poor quality PC laptop touch screens generally come from starting with a low quality display, backlight, and plastic screen (instead of glass) to begin with, not the touch layer.
If Apple uses the display tech they are rumored to be using, the touch layer is going to be there regardless of whether Apple enables it or not. Nor does Apple need to adjust any UI in MacOS elements for touch is a secondary input method. Touch screen PC laptops don’t run a different version of windows. I stand by my point that simply adding a touchscreen to a Mac (and doing nothing else) doesn’t have a consumer facing downside, even if you never use it.
My thoughts about where Apple wants to take iPadOS are separate from this, and would have consumer downsides. I do wish iPads running macOS, switching to an iPadOS UI when undocked were on the table.