A cabin opening to the outside deck has pros and cons. The pros are that you only have to open the door and stick your head outside to feel the temperature, and you have quick access to the outdoor deck for viewing the scenery and wildlife.
The cons of a cabin opening to the outside is that you always have to go outside on the covered deck when going from your cabin to the dining room, observation lounge, or elsewhere on the ship. If it is raining and the wind is howling, you might get wet! The cabin temperature might also be harder to keep regulated if you are opening the door frequently.