Because there is no ****ing small and light Mac (preferably with a detachable keyboard) with cellular for me to buy.
Even if there were, I'd prefer to travel with only one device, which means I'd lose out on all the stuff the iPad is actually better for.
I'd happily pay $10000 for a device that actually does what I want.
The whole point is mobility, so no, it does none of what I want.
I am more than happy with my desk situation.
I wouldn't care if the touch interface was disabled altogether in "Mac mode".
So a Mac with a detachable keyboard. You don't want an iPad, you want an improved Mac
Personally, I'd be happy enough with virtualization support on iPadOS, which would also remove practically all the security concerns you could possibly have.
Like I already said, allowing the iPad to run Mac apps (sandboxed) would be a workable solution. Like how you can run certain iPad and iOS apps on M-Mac.