For Apple specifically, it’s because it would cannibalize the sales of the iPad. They’ve pretty much got the tablet market cornered, the iPad is considered the only “good” tablet nowadays and by far the best selling, and they’re NOT giving that up. They’ll gladly let you sync your iPad to your Macbook to get a similar effect as having a direct touchscreen input though! How nice of them!

Well if you want touchscreens for doing stuff quick, keyboard shortcuts do the trick even better than touchscreens in my opinion.

Because on a laptop, where you are going to use the keyboard, it’s just easier to use a mouse. Raising your arms to touch the screen is less ergonomic than just reaching for a mouse or trackpad.

As I see it, touch screens are not the best thing for productivity. If you have to keep your hands raised in the air for a long time, you will get tired. Unlike having to rest on the table or keyboard.

So even if you add a touchscreen to a laptop, you won’t use it much so it is smarter not to put it in the first places. Smartphone and tablets are not productivity tools. You use them with too fingers at most, for mostly consuming media or casual chats on the smartphone.

I am not sure you can comfortably do programming work or some heavy excel editing or whatever exclusively on touch screen (hands raised in the air and/or extreme hunchback)

At previous place of work, they provided dell XPS with touchscreens or convertibles to executves and directors. I rarely seen them use the touchscreen while working even if they knew of the feature. It was mostly occasional scrolling, clicking the start menu, or minor things like that.

I also guess that there isn’t a sufficiently high demand for it.