Ya Rick, I'm still dealing with Vertex lighting for interiors on City of Heroes, so all my big areas are broken up into 8' segments for the close LOD and 16' segments for draws past 100' or so. Past that you can't really tell that the lighting is changing.
You can also have shading issues. I'm not sure how important that is in this day and age with per pixel lighting, but certainly back in the olden days you had to avoid large polygons, and long thin triangles because of vertex shading. Anyway, dividing it up into more polygons allows for texture tiling.