The biggest issue with Garleans is they cannot use magic. That would be a problem lorewise in a game where everyone can play any job. The inability to use magic was the driving force for Garleans to develop Magitek, and their early national story that they were victims of every other race until they became stronger and started conquering.

Personally, I want to see Viking as a tank job. The game needs more shield using jobs, and more blunt weapon jobs, and Vikings in their rare appearances use hammer and shields.