When detailing objects, the object is often isolated in the detail to do the detailing. When that object was sitting on a platform, or an upper floor, the ground plane will be drawn at its usual height, giving the impression that the object being detailed is floating in space. The wish would be for an option of having detail specific ground planes, where only the objects visible in the detail would be considered for the automatic height, of it the user explicitly sets the height, it would only affect that detail.
Thanks,
Sam