Why do people have theme rooms? What do they mean?

Someone at work rose the idea that women have a favorite animal that is used for decor. For example, this guy's wife collects chickens. (Couldn't help giggling.) I don't have such an animal, but I'm usually off the norm on girly things, so I asked around. The people I talked to didn't have animals, either, but they brightened when the idea was broadened to "theme rooms." Lots of women decorate with foreign locations--either places they'd been, would like to go, or had some kind of genetic significance. I, myself, want to do the kitchen with a cross between Hispanic and Greek influences (pine and teal, pine and teal). I'm not sure whether it's a good idea yet...