I don't suppose NATS or other ATC organisations are banning the flights lightly. After all, if the aircraft don't fly throught their airspace, they don't get paid either.
The decision not to fly has been made internationally and for the right reasons. Can you imagine the furore if an airliner flew in these conditions and came down over London, Amsterdam or Frankfurt? It is inconvenient for all- crews and passengers alike, but unfortunately, so be it.
I am happier being down here wishing I was up there rather than being up there wishing I was down here!
The real trial for all the airlines will be next week when it starts to get back to normal- not only are crews in the wrong place, but my company have crews stuck downroute on what is now their days off- they will need extra unscheduled leave to compensate and this will impact on ALL the crews, so I suspect much disruption for the next week or so. And THAT assumes we will get back into the air in the next day or so!