For crying out loud, Apple, just build a touchscreen Mac already

No, hell no. Desktop UIs — whether macOS, Windows, or any of the Linux environments — are not suitable for touch. They have to be gimped or uglified in some way to be touch-friendly; just look at the Windows 8 "Metro" disaster.

They are certainly not comfortable to use for long periods; just try using the Windows Classic Desktop with only touch for an entire day, without reaching for a mouse or trackpad whatsoever.

There is also the notion of active/focused windows in desktop OSes; on an iPad you can simultaneously interact with and truly control two apps at the same time, using multitouch in side-by-side split-view, but on Windows/macOS/Linux this creates some hard problems:

If your fingers are each on different window, over a different control of different apps, which apps receives keyboard input? Which app should get to display its menu? Which window is foreground and which are in the background?

If you need to draw in desktop apps, you're going to need a dedicated drawing tablet anyway, or you could use an iPad Pro + Apple Pencil with AstroPad [1] or Duet Pro [2].

[1] http://astropad.com

[2] http://www.duetdisplay.com/pro/

Omg please don't, I can't stand touch screen computers, keep concentrating on privacy avocation and OS X stability and performance.