Belmarduk,
While you are quite right that the Gamebryo client is a 3D client, UOKR is still a 2D game with sprites and everything. We take advantage of a 3D client with things like the particle systems, but everything in UOKR is still 2D. If you were able to swing the camera around, it would look as though you were looking side-on at an image painted on a sheet of glass. Converting UO art from "2D" to "3D" would be a fun, but extensive undertaking. Sadly, there's no 2D/3D switch that can be flipped to turn everything to 3D.
-Grimm