all our kttw cards our cruise (cruise only) unlocked the door. You had to have everyones card to get on and off the ship.
We did have charging priveleges turned off! Disney does not place spending limits on the kids cards, and they can charge, charge, charge! We turned our kids charging privelages off the first day, but the card still worked great as the room key. In fact, a hole is punched when the charging is turned off.