I'm not so sure the people are seeking 'what to design'. Back when the @Last started the Gallery Forum it became obvious to me from the postings that users were very much split among two very different ways of using SketchUp. If you think about it I'm sure the same differences are still apparent today...
First there are the users who use SketchUp to model something already designed. They are using it to 'illustrate' or create visuals. Then there are other users who use SketchUp to design -- using modelling not as 'proof of concept' visualizations but to explore and develop ideas not preconceived. Of course many users do both approaches depending on the project. Its not about one use of SketchUp being better than another.
I think the new users of SketchUp from a CAD or illustration background are likely to be quite comfortable with a teaching approach that focuses on building a visualization of an existing design. In contrast those who want to understand how they can use the tool to 'design' better, faster, etc. might find that visualization approach lacking. Sure they are seeing how the tools work but they may not really be 'getting it' with regards to how they could be using it. Of course the tools do work the same way for both kinds of users. I really don't think it would take much to help those users get more from a course...
I don't know how courses in SketchUp are typically taught so maybe my ideas that follow are already par for the course. Perhaps a course should always start with a slide-show of how others are using SketchUp. With images from the Gallery here or from the case studies at the SketchUp site, it could highlight for the new user what other people using SketchUp do with it and the diversity possible. Having such a show right upfront establishes a few things. It makes clear it is ultimately a flexible tool and that there isn't just one sketchup 'style'. It can help establish the 'goal' of being accomplished enough to be able to communicate effectively using 3d. It can show them the fun that is possible. It can show that it can be used to explore and develop ideas, basic or complex, or as an illustration tool as loose or as detailed as may be desired. I remember the DVD presentation that Paul Miller put together to show his coworkers the potential of SketchUp. It was such a slide-show that very much communicated that SketchUp very much could be a tool for personal expression - a creative tool.
I also think a course could include some design-oriented tasks that would help participants see first-hand how it could be used for massing studies, or other form of exploration. What some participant's will 'get' from this is that SU really is a tool they can use even if they never see themselves developing a detailed model.
Regards, Ross