While we're playing the opinions game, I think that an iPad running macOS is absurd. A super awkward touchscreen device running an OS that's not touch optimised with interface elements that are too small and close to accurately hit, that is severely thermally limited, and will throttle whenever a slightly demanding task needs to be performed. I think that touchscreen laptops in general are an ergonomic mess that don't bring anything useful.
They're just opinions though. They're valid for me, but they're not universal rules.
The great thing about the iPad is its versatility. There isn't a wrong way to use it, and everyone adapts it to their use case. Mine iPad Air 2 is locked into landscape because that's the way it works best for me. One day when I have the money, I'll upgrade to a 13" iPad Air, because my eyes are crap, and I want a bigger screen.
Yes but Apple would not release Mac OS as it is now, on any iPad Air/Pro with an M chip. They would release a Touch optimised version of Mac OS, probably locked down to the App Store (i.e. no sideloading of Mac Apps) like iPad OS. Any thermal throttling will be similar to the Macbook Air, as they are essentially the same hardware (fanless design).