figured it was worth asking about and the reasoning makes sense. though in the scripting manual it also says that things like Rot, Offset and Pivot are also listed as get only:
PVector3 Scale { get; }
PVector3 Rot { get; }
PVector3 Offset { get; }
PVector3 Pivot { get; } // the pivot of scale and rotation operation
even though you can have a script modify those temporarily. are those only modifiable because those aren't recalculating all the data per frame, just that one attribute?