That was Mythic's approach with Warhammer. Somehow they still managed to make and break promises though.
Having an approach and following it are two very, very different things.
War launched with such a fraction of what it actually promised that I can't take it seriously that this was their approach. I mean, missing 2 promised classes and 4 promised cities is pretty bad.
And they were releasing stuff ALL THE TIME. I got stupid emails every few weeks with whole new races and classes.
With SE, I'm betting they will show new jobs as time goes on, not give them all at once.
Like, one update might show a Warrior and Blm. Another might unveil the Thf and Pld.
Whatever they are sure will be done in time.
And, if there are advanced jobs, you know they'll be unveiled later. If they have to choose between completing the Blm and Smn jobs on time, it is pretty obvious which they will choose.
They'll also be looking for balance. One of the stupid things about War's launch is that they failed to launch one of the tank jobs for only one side. Realistically, they should have benched the other side's tank as well, instead of beginning the game unbalanced.
There are a LOT of factors in releasing info. Breaking promises, the balance between hype and reality, the risk of information souring over time, fear of other games overshadowing your own, etc.