Classes in this game are not classes as we usually see in other games. Classes are the guild where you learn how to use your main weapon, for this reason, in jap, they re called with the name of the weapon you re using. For example you learn how to handle your spear then you became the actual class that is DRG job. In my opinion the best way to change it not going through a complete alteration of this system is to low the level when you get the job and to give more jobs specific skills, doing so it will have a sense to add more jobs for each classes (not the non sense hybrid they ve done with smn and sch)