Interesting idea - I can see that idea possibly working on, say, the North Atlantic Tracks on a good day with serviceable aircraft, passengers and cabin crew , but I'd be interested to understand how a lack of 1 to 1 mapping would work out in the even of sudden closure of large chunks of airspace for weather reasons ( happens over the States in Summer on a regular basis most years putting a very high work load on all controllers and all crews) or the even more extreme, and hopefully never to be repeated, scenario - 9/11, where "our" airline had aircraft either being told to land somewhere suitable ASAP "your choice but don't come here", being forcibly told to go to airports they couldn't land for performance reasons (they didn't), or being simply told, regardless of fuel, to turn back as they were approaching an ATC Oceanic Boundary?? I know many people were very grateful for 2-on-1 mapping that day and personally I doubt less than 1-on-1 would cope for 100% of aircraft in the time and with the fuel available.
First, I'd like to reiterate I'm not necessarily supporting the idea - I just think it's an interesting thought experiment.
But... The situations you describe in fact sound like exactly the kind of thing automation would make much easier to manage.
Algorithms already exist to solve routing problems in much more difficult problem scenarios than airspace (by 'more difficult' read 'more constrained.') Computers have been solving that sort of problem for decades; for an example you use every day - note that the Internet seamlessly and automatically re-routes data packets via alternate paths even when there is a massive failure in the middle of the network - much much more quickly than a blink of your eye, let alone the time it takes you to contact ATC, and in far more constrained and congested 'airspace.'
Of course, planes aren't packets - but from a fundamental algorithms point of view these are solved problems.
From an ATC point of view, having half your airspace do exactly what it's told simultaneously at the click of a button to route round the closed airport/weather system/whatever, gives them more time to manage the remaining planes with their unpredictable meat-based computers.