What are the principal advantages of creating a conceptual design model using masses before diving into the detailed design and building element modeling?
The conceptual design phase allows the designer to play around with the general idea of the shape of the building, so that they can get creative with the look and verify that it will work on a surface level (functionally/aesthetically) before diving into any more momentous levels of decision.
Should all buildings be modeled first using conceptual masses?
No, not all buildings should be modeled as conceptual masses. Only large buildings with lots of floors should be modeled this way because they have many floors that will just fit into the geometry, whereas smaller buildings should be built around the function. It’s of course okay to have a shape in mind for smaller buildings, but going the extra step towards building a mass for it may obscure the minutia of a smaller building, since it will be trying to fit into a more abstract mass, when there is really no need to do that, if you’re only placing a few walls/floors/etc down.