I recognise the problem of dealing with public perception of danger, but I do feel that the reaction to this problem seems to have erred strongly toward risk aversion rather than risk management.
The ash plume is a three dimensional and largely predictable pattern. In the military we had algorithms for managing flow patterns (eg downwind chemical hazard); we could then operate around the threat. It wasn't difficult science. Why doesn't NATS have the same approach? It seems to me that they have taken an overweening approach.
More pertinently enormous areas of operating airspace appear to have been closed down, but not by operators. Operators deal daily with operating hazard - it seems odd to me that nobody is equating ash with dust/sand that forms a routine risk assessment in many parts of Africa and Asia.
Just a thought. But many correspondents might like to dwell on what they are told to do (and readily accept) by people who never step out of the bunker - and what the rest of us routinely manage as part of our daily approach to life.