Sunfish
As for comments about "commercial considerations" and individual airline decision making those are also way off the mark. Aircraft Insurance contracts and lease agreements would most definitely preclude doing anything not approved by a regulator, which is probably why Ryanair so promptly grounded its fleet in my opinion.
To put it another way: You would all be screaming about why the regulator didn't ground aircraft if half the fleet was now ash damaged and out of action for months.
Your arguments are tiresome and not borne out by fact but only by your own imagination.
Your opinions have been registered, just like the rest of us. Hopefully you can't go on and on arguing to convince others by citing the same old "what ifs" that can not be backed by facts.
Regulations are codified, judgements are not.