I recall him saying they were thinking of not making it as simple as just leveling one class to 30 and then unlocking the Job. One class to 30, another class to 15 => ability to unlock a Job.

If classes are to receive more than one Job in the future, there will be some interesting problems the dev team has to solve. If you toss one class a bone, you need to do the same for all other classes.... current and future. 2 Jobs per class? Every future class needs to have 2 Jobs as well, by default.

If they implement one Job per class, they will have an easier time in the future as well. They still need to bring both class and a Job to the game at once (well, nothing says they have to, but a class by itself won't be of much use), but at least it'll be easier than to implement a class and 2 Jobs at once.

They could also implement shared Jobs to keep the classes on an equal ground without having to do so much work in the future. But other interesting issues arise from that; if Jobs follow a class (and vice versa) in level progression, which class should these Jobs share their levels with?