I'm not the OP, clacko, but I can offer one thought. Disney offers child care at all ages, which no other cruise line does. That way mommy and daddy can go to the spa, have an elegant dinner, or go dancing at a club with complete confidence that their little one is being taken good care of.

Of course another reason is for people like me who simply love the Disney experience and quality--I'd sail Disney even without kids at all!