Symbology plays a vital role in the communication of cartographic information. AutoCAD Map's inability to represent linetypes for 3D polylines is a severe cartographic limitation. AutoCAD Map should consistently represent the linetype of all objects in the drawing regardless of whether they are co-planar with the WCS. AutoCAD linetype representation should be independent of the plane to which the object is oriented in the drawing. In other words, a dashed line should show as a dashed line and should look the same at all times.
This is something that needs to be dealt with at the core AutoCAD level, rather than tacked on as an option or system variable only in the Map product, and it should be the default behavior. Since symbology represents neither drawn angle, nor viewing angle, it should be independent of both. If there is a need for symbology to change with the viewing angle, then it should be an option controlled by a system variable.