It certainly seems to me that not enough data gathering is going on. The handful of planes going up through the levels and hanging around for an hour or so trying to make a point didn't really prove much because they couldn't measure what level of ash they actually encountered.
The NASA document on their accidental ash encounter was a real eye opener on the insidious danger posed by the cumulative effect of diffuse ash. Certainly scared me.
Ideally we'd have got all the military/scientific aircraft available worldwide flying round and round for as long as possible over the last week then getting their engines boroscoped/stripped down in an effort to quantify things. Until we're able to say something like x g/m3 = y safe hrs between boroscope inspections then we're stuck I'd guess.
Without this aren't we looking at a future of trying to operate long term with long periods of lockdown followed by massive repatriation efforts. Would the public adjust to that, going on holiday thinking they had a 50/50 chance of getting home on time?
Unless we put this volcano out of course. I saw this cartoon once and all they needed was a really big bucket of water.