I would say one reason they didn't attach these to any jobs was to reduce the amount of people leveling it off the bat. Had they had ROG abilities that other jobs could use a lot more people would of pushed through to level up to at least 18 to have the two must have abilities if their job could use it. But there is also something else to keep in mind.

The current job system works under the assumption that they can only draw abilities from two other classes besides their base class. SMN=Archer/Thaumaturge, SCH=Conjurer/Thaumaturge, BLM=Arcanist/Archer, WAR=Pugilist/Gladiator etc etc, which means they would of had to change the rules that jobs abide by.