I don't think it's the possibility of a disaster but how one evacuate a ship with so many souls. On the few new(er) cruise ships I've been on (all <2,000 pax and assume about 50% of that in crew), I can't imagine an orderly and calm evacuation unless the ship is absolutely level and slowly settling into the water (or if not, on fire but still able to evacuate in an orderly fashion). The Costa Concordia loss probably didn't have greater loss of life as the ship came to rest on its side and was very near land as well.
Next "cruise" I'll be on takes me from East Asia to west coast North America. Only 24-26 crew, maximum of 10 passengers, enough space and immersion suits for all in either of the 2 lifeboats. If it came to evacuation, I'd imagine one has a better chance on that than a cruise ship on the same route.