One reason might be that, if you buy a Macbook with a touchscreen, there is less reason to buy an iPad in addition to the Macbook.

I had one laptop with a touchscreen and it was so annoying that I disabled it. Every time I would brush something off of the screen, or someone would point at my screen and touch it, unexpected things would happen. Keyboards are much more efficient than touchscreens, so there didn't seem to be any point.

They're probably right about that. But they could put the pin sensor technology from the iPad Pro into an iMac and get a pretty good product. They did a fantastic job with it.