Not all walls conform to industry standards. Some of the more interesting buildings to date couldn't be designed using Revit's standard components or by conforming to industry standards (EG: see Zaha Hadid Architects, Santiago Calatrava and so on).
A. If I have a wildly curvi-linear element in 3 directions and I wish to define that element as a wall, then I should be allowed to do so. Generic modellling is required therefore a means for defining a model within a family is required.
B. The wall tool per-se is limiting, which is fine for a dull rectilinear box but Revit models complex forms very well. Therefore, one should have some means available to define a complex form as belonging to something. In revit everything has to belong to something, as far as I can tell.
C. I'll want a door in my compex 3d wall and I'd like to move that door about as I would in normally in Revit. In other words, the wall is cut when my door is moved or I decide to add another door. We might just as well go back to AutoCAD if all we're doing is sculpting in digital space.
D. I want my complex 3d wall to appear as a wall in my scheduling. I have seen (and specified) walls that are made of GRP precisely because they are defined by a complex geometry. They are still called walls.
Thank you.
Simon Blackburn RIBA