The benefit of traits vs. classes is that I can add *functions* to existing objects without needing to modify a monolithic definition.
The benefit of ECS vs. structs is that I can add *data* to existing objects without needing to modify a monolithic definition.
Conversation
Replying to
"You can have it all: abstraction and good cache performance" was an interesting paper relevant to this, attempting to abstract over SoA vs AoS styles of programming: doc.ic.ac.uk/~scd/ShapesOnw