What are the principal advantages of creating a conceptual design model using masses before diving into the detailed design and building element modeling?

You are able to control the shapes and figures within the model in a more creative and free-flowing way, as opposed to detailed modeling with walls and floors from the beginning. By conceptualizing the model initially you are able to hold onto the freedom and expression of more abstract components and designs.

Should all buildings be modeled first using conceptual masses?

For smaller things that are basic in form and function, it may be too much work to try to conceptually visualize it as masses if it is a simple structure. For other projects that are more creative than basic forms, conceptual masses are helpful in creating free-flowing movement and shapes in the model