I.E. Here's what I'm talking about, even Hollywood and Disney have this problem and are trying to solve it: http://disney-animation.s3.amazonaws.com/library/s2012_pbs_disney_brdf_slides_v2.pdf
In fact, their BDRF sounds pretty good! "As few parameters as possible, 0-1 range, all combinations of parameters plausible" Mmmm yeah that's the stuff. One BDRF to rule them all, one BDRF to find them, one deferred renderer to bring them all, and in screenspace bind them!