Sure 2d elements should inherit original properties.
For legacy matters, all elements (2d or 3d) should have at least one Property that can be called "Layer" in wich there is an "Archicad Layer" by default that can't be deleted, but you can add more itens in a dropdown list checkbox. Old project can be acessed by converting "Layer" to "Property Layer".
The current layer system, is a binary one. You have to choose what you
want
to see, and what you
don't want
to see for each Project and View Map. The logic of a Property Filtering system is much more advanced than this. For a simple example: I can create a Property called "View Maps Property", that could list all the available View Maps on the project with a dropdown checklist in wich I could check all the View Maps I'd like that element to be seen.
Then I'd create a Property Filter for each View Map that would Select All Elements that its "View Maps Property" contains "Current View Map". The power of a Property Filtering system is endless and can suit all the user possible needs.
IMHO Graphic Overrides must be kept doing what it does best. Wich is: Graphic Overrides. Not visibility control. Adding a visibility control to GO would add another level of mess that Renovation and Parcial Structure Views already are.
We already have misdescribed elements in the current Layer system. Misdescribed elements are just matter of Project hygiene.
But anyway... I am not trying to persuade GS... It is just a sugestion.