Look, Pixar fakes reflections, ILM uses dirt maps to roughen up their robots and vehicles, WETA Digital uses pictures of fire on cards to simulate flame, and they all STILL have to do hours of post work to make it look "real", you can't honestly believe it works any other way. Most films are shot within the first 8 months to a year or so of production and the rest is all post work and special effects. When you consider most films take two years to make, that's a lot of post production and a lot of tweaking renders. Good lighting can make a bad model with crappy textures look great and while it's true that radiosity isn't always used, wanted, or needed, it does help in evening out the light in an indoor scene which helps make the overall image more real. I suggest taking a look at Jeremy Brim's book on lighting as it will help you understand why it's so important. Oh, and everything, even the smoothest surface known to man, has some form of texture to it. That smoothness in and of itself is a texture by definition. So, go out there and find books on the studios or the films that you like and see what you can learn.