At the moment, Revit families are generated as surface models (read How Revit families are generated).

The advantages and drawbacks of surface and volume models for products in the luminaire and sensor market are marginal. 

The target is the same in both cases; at the end of each configuration, the planner requires a clear indication of a product that is described precisely in technical and commercial terms.

Advantages and drawbacks of surface and volume models in Revit (Versions up to 2018):