Thing is, your craphic card does the lighning only if you do the proper textures for it. Its the 2D artists job in both cases. Needs the same thinking in most cases, I mean you have to know which parts should have bump, which parts need highlights. No card will calculate that for you, not to mention that would need zillion polygons to make it real. So you have to tell the card with a texture where to do it. Or you fake it onto the diffuse map. Same story, personally i find the first approach a lot more fun, naturally the latter gives nicer result.