Published in 2002. At that point, ANN research had reached a pretty hard plateau with very few tangible results. Faulting Russel and Norvig for not going into depth about ANNs is kind of like faulting Richard Feynman for not going into depth about quantum computers in the Feynman Lectures.
Also, a lot of the subsequent work and breakthroughs on ANNs has been done at Google under Norvig's leadership as Director of Research.
