Yes I agree about the engineering tradeoffs that require but the point is, as you hint, that they are actually already there and it's mostly a business decision.
I have tried the iPad Pro dock solution and it's exactly what motivates my argument. The floating aspect is largely pointless and mostly serve as a look thing (if anything it makes it more tiring to raise your hand to use touch) while having stability compromises, and not providing enough advantages (they just added a port, the trackpad is small but at least the keyboard is better now). I don't think the weight argument is very relevant since the combo already weighs more than a MacBook Air. The point is to make it a more complete professional device, something has to give, MacBook Pros are heavier and people deal with it.
To keep weight down they have the Air line, this is what it should be for, not selling re-heated designs at a discount (but of course the bean counter will disagree with that).
They could make a much beefier base, with more ports and actually invest some engineering into figuring out a great hinge mechanism that the iPad part could lock into. They wouldn't need to rework a lot of the iPad parts and with their current chips you could get double battery life for what would be a very modular powerful device.
Apple used to be able to do that, I don't know if you have ever dismantled a "Sunflower" iMac but I can tell you it was great engineering. I wish they would work their ass off to deliver something "magical" like that.
But they won't because they know very well that many pros already get by just fine with a MacBook Air but they need to buy an iPad on top of that if they want stylus/touch functionality.
You can infer that because the iPad Pro uses the same exact chip as the MacBook Air and the device drivers must be extremely similar outside of touch/stylus and camera. If they wanted, they could at least allow dual boot macOS/iPadOS with not much work at all. The touch target is a poor argument since it would work just fine with the stylus and using Wacom displays with a Mac has been a thing since quite a while now.
It's purely commercial greed that motivates their behavior and it's the real reason they don't even try to make a device like that. One could argue that it's too niche, but that would be quite an argument, considering Apple just dumped billions of dollars in a Vision Pro, that ironically lacked vision and is the exact definition of niche. The problem with VR headset was never a technology quality problem in the first place but the fact that it doesn't really enable any kind of usage that goes past the cool demo to make up for the massive tradeoffs in useability/convenience.
So, you have Apple dumping billions into a stupid "me too" product while purposefully ignoring a potentially innovative device because they are afraid that they would lose money. I doubt we would get the iPhone today if Apple got as successful as it is with just Macs/iPods.
I haven't used an Asus Transformer but I have used a Surface Pro and my brother has a Surface Book. The potential is there but they are clearly let down by the comparatively much worse hardware. And that's the point, for anyone else than Apple this type of device is very hard (especially since their volumes are much worse) but if there is one company that has every building block that could make this go from very cool concept to absolutely amazing it's them.
And yes, I agree that on a regular laptop having touch is not that important, you need to enable the tablet/flat notepad use cases to make it worthwhile which is exactly why 180/360 laptops with special hinges are still a decent target. But Apple could do it all.
