There is a marketing aspect to modeling that maybe even your client isn't aware of. Placing a model of ones business or building in GE is not about the model, and making it so that people can do a walk through, which would not be possible without making a much more accurate model for that to happen, which you have already alluded to.
The marketing aspect of a simple model, uploaded to the 3D Warehouse and placed in Google Earth is that it gets premium indexing priority from the Google web crawlers. SEO is the benefit of having a model present in GE, and now if the business has a "Google Local Business Listing," that information is now tied to the models description.
All of that can be present on a web page also using the GE API, so there are some business benefits to pulling up a simple model for GE.