I'm going to give you the opportunity to respond with some logic and sense.
Right now, the way it is. And what I gathered from this persons post has nothing to do with "wanting to level 2 jobs at once."
What I gathered, was exactly how the game currently exists, but making a bit more sense of it.
That is....
AST magically being level 30 when you unlock it. Instead of the same level as say RDM and SAM, or even GNB and DNC.
But they dont.
For no reason.
To me, now THAT is nonsense.
What this person seems to suggest, is that there is a bit of consistency.
Since SMN and SCH are the only shared jobs, and they have this mess of other jobs magically unlocking at different levels, he came up with a very good idea, to make it all streamlined. The new jobs for each expansion piggy backing off of base classes.
This gives the choice you make at the start a whole lot more meaning, instead of, "oh look you're a class that will become completely obsolete at level 30 for no reason except we were too lazy to write in better lore, or change the system."
So, with keeping that in mind.
Please tell me, how the current system is not nonsense, and why its better than the proposed idea? Because literally you're already in a way leveling 2 jobs at once, when you do the Main story quest, you unlock new jobs based on that level. So yes, yes you are leveling 2 jobs at once..... at completely random levels mind you. AST 30, SAM 50, DNC 60.
Its just your second one gets stuck at a random level along the way. For absolutely no reason.
So ...
To break it down for you even further.
-Idea:
Streamline all classes and jobs to make more sense. Specialty jobs (new expansion jobs) piggy back off of existing base classes.
-Current system:
Unlock jobs at random inconsistent levels based off the expansion with no lore for the reasoning behind it.
AST, MCH, DRK level 30
RDM, SAM level 50
GNB, DNC level 60.
With future jobs randomly unlocking at even new pointless random levels.
-Your reasoning:
(What I would consider a response from someone who disagrees, and the points they would hit in their response.)
-Why should the current system stay in place. (Jobs unlocking at increasing levels per expansion.)
-Why is the current system not complete nonsense, and horribly inconsistent. Especially with the mindset of a brand new player starting at any given expansion.
-Why do you think inconsistency is good.
-Why do you think it should not be coherent.
-Why do you think there should be no meaning, even a system based meaning such as this, behind base classes, especially when something such as this would actually give impact to base classes without changing a single thing?
-Edit: And why is this idea, "bad" or any different from Square-Enix throwing Exp and levels at crafting and gathering classes, and selling level skip potions in the mogstation?