You are not required to touch the screen of a touch screen computer..
That is correct, I see no problem implementing touch / pencil support as well as trackpad support. Anyone that has used an iPad for any length of time then switches to a laptop has spent time poking the screen of a MacBook. There are different use cases for different interfaces and each one is superior in specific cases. The thing is these use cases are not limited to just a desktop or just an iPad but can cross function depending on the use of the device. There are usually UI guidelines on what should be implemented for what device already. Some of Microsoft's toys have real world potential if implemented correctly. The different use cases that are obvious to me are:
- iPad Pro - where you are using it as a consumption device or as a tablet (i.e. without a keyboard/mouse)... where you want to use touch and
- iPad Pro - where you are using it primarily as a laptop hooked up to a keyboard and mouse.
- Laptop - where you have a permanently attached keyboard
- iMac - as a desktop with keyboard and mouse
- Microsoft Studio - where you are using it as a large easel to draw or as a console dashboard
- Mac Pro where you really are only using it as a desktop.
The functionality of different input is not limited to a specific use case but can cross uses. You would not have pencil support on a Laptop as ergonomically it would not make sense, but you could have it on the same device if you pick it up to draw with it without a keyboard. You would not use a pencil to draw on an a current iMac, but if you had an iMac that you could pull down in easel mode then pencil support would make sense (and yes there are real world usecases for this professionally). If you are using the 2-1 as a tablet and dock it to use as a laptop then the macOS UI would be on average superior - but people are still going to have a tendency to touch the screen as it is natural to them and not having touch in that case is not user friendly.
The trick is having the applications already ready with cross use-case support and having an interface that seamlessly adapts to the use-case you are currently using. That is where Apple tends to have a long-term vision and does not give half-baked solutions to the user... but it does not mean they will not in the future. I expect they are and have been actively trying to work - and if/when they do have it ready for prime-time you will start to see it on devices.
Until then Apple will tell you exactly what it does and deny what they do not have an active release date ready for such a use. For the longest time, the iPad would never support a trackpad since it was a touch device... yet the trackpad is superior in certain use cases and Apple implemented it. The same thing with the pencil, etc. etc. etc.
