As I am currently trying to make an internal office standard, I have seen that some elements are not needed to be modeled, but must be taken into account for quantity take-offs. One way to solve this is to give us the possibility to classify and show lines, polylines etc into schedules, give them IDs and properties (thanks to classifications).
I'm not sure this is the good solution for BIM - to use lines and polylines to represent building elements for quantity take-off.
Use library parts instead. You can use existing parts (for example cube element to represent any rectangular shape on plan with or without 3D). You also can create your own GDL elements - even if you don't know GDL programming. Just draw line on plan and save it as an object.