I suppose this makes sense, since you can't take out your wrath on a volcano. Poor little Eyjafjallajokull just had to let off some steam. So who else can the airlines blame for all their mounting losses? The regulators, of course! British Airways CEO Willie Walsh said, "I don't believe it was necessary to impose a blanket ban on all UK airspace." This was echoed by airlines all over Europe. Many in the media have tackled the issue of whether to fly or not to fly, so I thought I'd chime in as well.
I support the regulators.
Is it possible that the skies could have been kept open safely? To some extent, perhaps, but in this situation, I'm glad air traffic ground to a halt to ensure safety wasn't compromised.
As the Financial Times article noted, the European regulators aren't used to dealing with this type of event, because it really doesn't happen (often). It's impossible to prepare for every situation, and this apparently is one where they weren't completely ready. So they did the prudent thing and closed down airspace.
Some have criticized the Europeans for not adopting the US model, which doesn't close the airspace but simply warns airlines about where the ash is. For the most part, when ash clouds occur in the US, they impact traffic in Alaska. But Alaska isn't one of the major capitals of Europe, so it's a completely different situation.
Others may wonder if the Europeans bowed to pressure from airlines and opened up airspace too early. I suppose we'll only find that out if an incident occurs, or if we see ash damage in engines. Hopefully we don't have to find that out.
In the end, there's no way to know if regulators made the right decision. I do know that it's the same decision I would have made. Airplanes have lost all engines after flying through an ash cloud so it's prudent to take extra precautions as they did here.