No, I am not wrong, GIFillIntensity defines the shadows inside the buildings (and with 0.4 could be enough). Check his pics, his statics are very dark and even in exterior surfaces
Sorry to press the case, but GIFillIntensity does effect the outside of buildings too. Picture below shows that default value (0.3) like Natty said does look very bad compared to even only slightly higher values. Also, you only need to type it in editor once, since it will store it in some secret location if you save your lightmap settings.
For further reading about basic static lightmap settings please see this tutorial:
http://fenring.bf1942.cl/tutorials/light.php