I guess it depends on where the door goes, but I should think there are practical reasons outside of sound quality to have the option of a door. If my listening room didn't have a door, my family would have hung me by now.
My listening room is open at the back, or I suppose a better way to describe it would be a C-shaped bonus room with the listening room being the top half of the C. Where it narrows to go to the other part of the room is open. I have found that adding a subwoofer in the back of the listening area really stabilized the bass in a way that has centered the music in the room better.