Actually, a lot of "very extremely detailed" faces have several detail parts modeled, like warts and whatnot. Bump maps just can't do the "fake extruding" at times. In fact, any details that will visually stand out shouldn't be planned to be shaded (bumped) out with a texture, they should be modeled as often as possible.

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram