The matrix is terrain, and the only other way to get terrain is to create a heightmap or something then use a 3d modeller to import the heightmap data and turn it into a mesh that you can export and then load into DB. What's nice about using .x objects as terrain is that you can use NGC collision with it, but I've noticed a slight performance hit, and texturing can be difficult at times.
If you need ultra detailed terrain go with objects, but if you just need some easy to manipulate terrain use matrices.

I'm going to eat you!