Advantage of exposing data model to customers using our product
One obvious disadvantage is that no matter how good your data model is, it better suit your needs for years to come because you will have just set it in concrete.

I try not to even give app developers access to the the underlying data model. There is a "wall of abstraction" between users and the physical data. That wall is build from a wide variety of views. Just about any format that best fits the user's need can be provided. View triggers do the conversion behind the scenes.

Give your customers whatever logical model best suits their requirement in getting their data to you. So you have to convert it to your current actual model. It sure beats not being able to fix flaws or implement new designs in your database.