In any case I think that the MacBook designs are stale and really stuck in the past, for now they only win because of the build quality and the silicon. But competitors are quite close, so if Apple continue with their destruction of macOS there won't many reasons to keep buying.
The point isn't to have the whole system of being able to be used with touch but to allow specific touch interactions depending on the context. It doesn't make sense to have big buttons and menus when you are going to hit them with a mouse/stylus most of the time regardless of touch interactions. This is a problem with all or nothing Apple approaches.
You can already see that with iPadOS: at first the iPad was basically a giant iPhone made mostly for content consumption and the touch only approach made sense because it was optimized to be used conveniently on a couch for relatively simple tasks. But as the hardware evolved and they added stylus support, software has gotten more complex in order to allow more advanced tasks. However, outside of purely artistic endeavor (where you use the table as a canvas to draw on) the UI who still has major focus on being touch centric stop making sense. If you are going to use it as a productivity machine, a keyboard is basically a requirement (why would you want to lose half the screen to display a virtual keyboard in the first place) and a finer pointing device (trackpad/mouse) becomes almost a necessity. At this point you end up having an overblown UI with large touch target that hinders information density/compactness even though you won't use it much that way. It makes the software not as good as it could be and forces poor use of the display space.
You end up in a weird place where the high-end iPads are completely overkill for the typical media consumption tablets were targeting but at the same time it's not a very good productivity device and not just because of the locked down nature of the OS (that only adds insult to the injury) but because it ends up being poorly optimized for that use case.
And this is what I fear they will do with MacBooks: a weird middle ground where you have to deal with the tradeoffs of both interactions methods instead of enabling touch/stylus in the specific parts where it makes sense. There is no need to have macOS fully touch compatible, only to support touch input in specific apps/use case where it makes sense. On top of that, Apple already knows how to transform a device for another use case just with software: in the 2000s they had Front Row, which allowed you to transform a regular Mac into a media center to be used with only a remote. That was just a software layer on top of the standard OS.
With the compatibility of iOS/iPadOS apps on Macs thanks to Apple Silicon, there is no real reason they couldn't just create this type of software layer that could enable fully touch centric use case on top of the regular productivity use case. And keep other parts of the system as they are just using the touch layer for the most commonly known use cases inside of apps (mostly scrolling/navigating, rough selection, etc).
But they don't want to do that because they are trying to sell hardware as much as possible, so they would rather make any given device miss a piece of the puzzle to force buying another device.
As far as I'm concerned, they could have made an iPad/MacBook hybrid for a long time now, where the display part could snap on a keyboard base and change primary interaction method accordingly. They won't because it means a single device could fulfill all the needs for most people who don't need heavy computing power.
In many ways Microsoft approach is actually better/smarter but they are being let down by inferior hardware (and to some extent the general hate on Windows, which is somewhat deserved but not as much as people make it).
To return to my parallel, at first Apple's approach with HiDPI led people to believe that they were ahead but, in the end, it was only a shortcut, requiring specific display resolution/form factor to enable proper integer scaling. It took a while for Microsoft to catch up, but now their solution is more flexible and allows for arbitrary resolutions that enables more different hardware configurations and ultimately use cases.
I feel it's the same problem. Apple is stuck in their ways and cannot let go of the touch centric approach, because this is what Steve Jobs argued for. They completely ignore that this argument was only about a mobile device that you carry in your pocket, where speed and convenience are the primary factors. And indeed, it is exactly what was needed for smartphones to be truly useful. But trying to apply this thinking blindly to every device regardless of their primary mode of use is self-defeating, yet this is what they are hell bent on doing it seems.
I've been an early adopter of this kind of thing (remember Asus Transformer?) and used it a lot. In my experience, the catch is that to make the screen detachable and usable on its own, it needs to contain most of the electronics and at least part of the battery, with the keyboard then becoming a dock with perhaps a battery extension. And the problem with that is that it makes the screen heavier and the keyboard lighter to the point where you can't have the screen at a comfortable angle when the whole device is on your lap (or if you can, it requires constant effort to maintain balance). It's perfectly fine if you have a desk or other such surface, but, well, it's a laptop, right?
Apple did an interesting thing with their iPad keyboard dock where instead of arranging it like a clamshell laptop, they suspend the screen above the keyboard, which allows them to move it closer to the user. I have one of those for a 14" iPad Pro. It balances better on the lap, but now you can't use it well while reclining...
That said I still think the concept could work, but it would require consciously designing around this problem. Personally I would be perfectly fine with stuffing the keyboard with more batteries as a counterweight, but I think that designers are reluctant to do this because it increases the overall weight of the device.
Anyway, on a device like that, yes, touch makes a lot of sense. On a regular laptop, IMO no (but with some exceptions; e.g. Lenovo's Yoga, and to some extent even Thinkpads because you can open them all the way to 180 degrees).
