Because I was the only one on the team who had 3D software, it was my job to block things out in 3D and render base images that other artists could paint over without fear of creating inconsistancies in scale, object placement, etc. The left side is what I would hand off to the other artists and they would polish it to the level seen on the right.
Another advangate of building the base in 3D was the ability to generate AO, light, reflection maps which I could hand to the touch up artists and make their lives easier.
