Why would you want greasy finger marks on your Macbook screen?
Not much point having a touchscreen on a Macbook (or any laptop really), unless the hardware has a 'tablet mode' with a detachable or fold-away keyboard.
Mouse and keyboard is still a better interface for A LOT of work. I have yet to find a workflow for any of my professional work that would be faster or easier if you gave me a touchscreen.
There are plenty of laptops that do have touchscreens, and it has always felt more like a gimmick than a useful hardware interface.
Maybe the end game for Apple isn’t the full convergence, but just having a touch screen on the Mac.