Without Dwarven Weapon Training, as it is, Dwarves do not make optimal fighters, barbarians, runepriests, warlords... basically... all the fighting classes that have been traditionally identified with the Dwarves.
Now, a variant world could work where Dwarves are typically identified as priests and communers with the infernal or dead stars, and that might be cool, but that would stray a bit too far from the standard idea of what a dwarf IS.
Dwarven Weapon Training (and Eladrin Soldier) are necessary for those classes. It's different that GGWP because Goliaths are a strength based class, so superior weapons AND weapon bonuses would not be appropriate for them.