Call me a bluff old traditionalist if you wish but given the very well documented risks of the effects of volcanic ash on aircraft I personally don't want some aircraft owner ignoring everything and leaping into the sky with the possibility of their mangled wreckage landing on my head. I would assume the government has a similar view and are protecting the general public at large (plus the cost of clearing up the mess left behind).
Not often I agree with you BD (well, never actually!) but you're right on this point. I really can't understand people claiming that NATS have overreacted. What other option did they have?