They had one in the master bedroom too didn't they? Personally I don't like fireplaces because they tend to be located where the entertainment system and big screen ought to go.
Civility is just a warm and fuzzy name for censorship.
The master bedroom appears to be made from the same set as the living room. It has the same bay windows and the same closet.
But I finally noticed the fact they have multiple fireplaces because in the Thanksgiving episode, Joan said she thought it'd be nice to have a fire in the fireplace after dinner and my first thought was "which one?"