Thanks to Bust and FastCo, I saw this great image of the actual set from the Addams Family, taken by Richard Fish. My photographic background makes me fully understand this set. The show was filmed in black and white and in order to get the proper contrast and color separation, of course, making everything in shades of green, pink and yellow makes perfect sense! It's like an analog version of cmyk. I had never even thought to consider what colors the set might have been but, I love knowing this.
Weird timing, too - I just last week showed Parker a few episodes of the original show. Her friends were making all sorts of Cousin It references and I felt it important to educate her on the subject.