Believe it or not, when decorating a room, you have to factor in door knobs, or more specifically what type of door knobs you want to go together with the new design of the room. It’s the small details that matter, so that in the end, when you look around the room or the finished product, there is a thought registering in your mind saying “something doesn’t look quite right.”
You want to pay attention to that, and try moving or changing small things, and not big stuff. So that in the end, you don’t feel frustrated. But in the end you have a feeling that now everything is perfect. Everything is right.
So yes, door knobs are a design consideration given that the ultimate goal of a design is to make everything flow naturally. So that the total package looks beautiful to the eye of the beholder, and eventual occupant(s) of the room.