CAD software is great for it's primary goal, which I see as to present blueprints, drawings, plans through static media (paper/PDFs). These drawings cover many topics (ex: architectural, civil, electrical, mechanical, plumbing, interiors, structural, hazmat, ect.) for a particular project. GIS wants to present topical data (storm drains, building footprints) at a regional scale. This data is most accurate in as-built plans. It takes real talent and diligence to understand CAD standards and how a drawing was created in order to harvest the proper information. This regional topological integration is most effectively done in GIS. Streamlined integration between these two softwares, as provided by ArcGIS for AutoCAD, could greatly increase efficiencies at agencies. Unfortunately, the problem you describe exists because CAD and GIS users are filling their immediate needs without a holistic perspective and unaware that both tools can benefit each other.