STL files are common among the CAD and CAE community. If they are of good quality (i.e. water tight, reasonable aspect ratios, no self penetrations) they often can be quickly utilized for CAD design or CAE analysis; however, if the quality is poor the task to clean them can be very time consuming. This is often the case for STLs which come from 3D scans.
The medical community regularly generates 3D scans of a patient's body part, such as bones, teeth, and cardiovascular systems and utilize them for design and analysis of patient specific solutions (e.g. dentures and stents). In the following video a STL file from a cardiovascular scan is used to demonstrate Altair Inspire's ability to quickly and simply go from STL to solid geometry; which may be used for design and analysis.