Sketches are great at revealing a concept. However, they often fail to engage and impress the customer as you would like. In other words, they don't provide the feeling of deep immersion and get the complete picture of how the space will look in reality.
Architecture models handle this task much better - 3d rendering vs 3d modeling digs more into the subject. Still, they can't ideally represent all the details that highlight the design. Most importantly, they often miss some aspects that may ruin the design. For example, lighting and the way it affects the visual perception of the space. Besides, architecture models require too much time and effort to build and are difficult to rearrange.