>* It doesn't sit well in your lap. So if you don't have a table and you want to type that's annoying

I'm not sure why there isn't a better detachable keyboard/tablet system out there. One of the main reasons I still travel with a tablet and a laptop (even if it's only a small Chromebook) is that the laptop is so much more ergonomic to just grab and stick on my lap which I often even do in, say, a hotel room even if there's a table available.

That's not great at all for your back though, so even laptop don't solve that perfectly. But it's the best we have.

Doesn't that pretty much describe the MS Surface Book?

Surface is better but it’s still not really like a laptop. Though probably comes closest. (I’m also not really in the Microsoft ecosystem so Surface isn’t that attractive to me.)