When you have a 3D rendering of your idea, it is easier to explain the concept to those working on the project.
As an architect, you will need to deal with contractors, government officials, construction workers, interior designers and more!
You need to be able to explain to them in detail everything about the project so they can do their jobs properly. With a 3D rendered image, you will not leave anything up to their imagination; they will have a visual to rely on and reference.
This is especially helpful when you have to deal with contractors and construction workers since these are the people who bring your idea to life; if they are clear on what you want to achieve then you will have crossed a very big hurdle.