Your queston will get answers saying yes and no.
Technically Disney says they prefer no jeans at dinner even on casual nights. However you will see a few people do wear nice jeans to dinner.
Nobody ever stops them or says anything to them.
I dont wear them, i wear slacks or capri's or a sundress on casual nights.
Pirate night I wear a pirate outfit or jeans and apirate t-shirt and bandana.
So just do what you feel good about. Maybe pack a nice pair but wait and see the first night how many you actually see in the dining room.
For soem reason the people on the Wonder see to be more casual the the people on the longer crusies on the Magic.
Kathleen