Are expert systems outdated, what are better alternatives to them, if any?
Expert systems went through a phase of increasing acceptance and then widespread recognition of their limitations (see Wikipedia). There are many references that consider cons e.g. Problems in expert system development (Kemp, 1993).
In more recent years recommendation systems have taken over some of the function you describe in recommending products to customers. A notable development or historical event was the Netflix contest for movie recommendations which led to a burst of innovation and interest in the area. Another aspect of your question involves learning patterns of human behavior and this can be done with ANNs and similar technology.