Most people are happy with a one-room system
If we all had the resources, we could have a dedicated video room and dedicated audio room. Not sure how the sound setups would differ, but most of us do not have the space in our homes or resources for something like that.
My observation is that if your primary source of sound is movies, you can get by with cheaper (and inferior) speakers. My cheap Sony speakers sounded fine for movies, and if that is all I used my Great Room for, I would still have them. They were NOT great for the classical music I like to unwind with, hence the upgrade to the Paradigm speakers.
As far as surround sound with music CDs, I like what my system is putting out, especially the ones designed with surround sound in mind.
Just out of curiosity, how would the perfect setup look for movies vs sound?