One of the key issues which the EC legislation was trying to address was where airlines encountered issues, which we all know happen, but then, for their own operational convenience, made a real mess out of the service recovery which was entirely in their hands.
I still object to BA, at times of LVPs at Heathrow, cancelling much of their short-haul programme, leaving long-haul untouched to meet the reduced landing slots, BUT THEN pretending the whole dislocation to the affected pax is wholly because of the weather, when the weather conditions are quite adequate for any BA aircraft to operate, but BA have taken a COMMERCIAL decision on which flights they will scrub or not. They need to make such a decision, but the rationale of sending off a string of half-empty 747s to New York, while once-a-day flights to Eastern Europe are cancelled, is a commercial/operational decision decided at the board meeting many months before, and not wholly attributable to "the weather".