I was one aisle over on the editor team. Your memory matches mine about how the BWS came about. It was about opening the system up to allow apps to easily be added unlike the original “trait”-based system that was closed by design.
Traits was the object oriented multiple inheritance archetypes layered on top of Mesa that Star was based upon and required a static analysis step of all objects in the system to optimize object layouts—this is why it was a closed system. After the changeover to BWS, a few years later, only the document editor, and all object types represented in documents (graphics, tables, equations…) continued to use traits.
Traits was the object oriented multiple inheritance archetypes layered on top of Mesa that Star was based upon and required a static analysis step of all objects in the system to optimize object layouts—this is why it was a closed system. After the changeover to BWS, a few years later, only the document editor, and all object types represented in documents (graphics, tables, equations…) continued to use traits.