The problem gets created because there is so many options about the looks in character creation that then dont get represented even closely by actual in game portraits.
NWN's solution to this was to add a bunch of "class" portraits that don't show any person but something representative of a character class. If there were some icons with things like sword&shield, book, dagger, magic staff, mortar&pestle etc. then you could pick those if there is no suitable character portrait.