I love a traditional space and I also love how the addition of moulding helps any room feel more polished and designerly, and a lot more high end. But moulding is actually not all that expensive, and depending on the type can be fairly easy to add to any room.
When I consider what to add to a space, be my own or someone else’s, I like to consider the style of the rest of the home so the home feels cohesive. I do not feel like craftsman style board and batten belong in the same house as an intricate and detailed box moulding. If your house does not have a style and is fairly builder basic, I think you can go ahead and define a style but once you have decided what you are doing, you should really try and stick with it.