Just throwing this out there, I think the problem is more that most of the classical BRDFs used in rendering are designed to be 'one-shot' in the sense they don't offer a breakdown for diffuse and specular terms. When a theoretical graphics programmer is using said BRDFs as intended, there's no energy competition between the two terms, and our 'diffuse Fresnel' problem goes away
. In fact, the reason we have these models more has to do with the rather crappy indirect lighting situation most games find themselves in-- we have to get a little more bang for our buck from existing point lights, etc. so we have a sort of multilayered BRDF approach that's designed to show detail not immediately in the specular area of influence.
EDIT: Yeah, I wrote this on reduced sleep and in a rush to get to work; I'm not sure where I was going with the whole GI/multilayer BRDF thing. See MJP's post below for a nice explanation of what I think I was originally going for