Here's my thoughts on this.

While i agree with OP that jobs need their own effort to give them more meaning and sense of fulfillment. However, as i mentioned before, this thread as many others prove how problematic this new Job system will be to the game when added as a 2nd layer on top of an existing class system.

I think this is essentially the biggest challenge SE will face with this game, nevermind 2.0, without a good well thought-out and satisfying battle system, this game will suffer grave consequences as this really is the core of the game.

It almost seems like SE is confused with their decision to put in both Armoury system and Job system in the same time. Where has this ever happened in the history of FF? Logical and normal way about it is to have one battle system in place. Let alone the fact that it helps avoid many other issues.

Funny enough to note, even looking at the poll rates, it's evident people as well are just as confused and you have a 50/50 rate, currently about 36 likes on each side. Why do you think? I personally think 'cause it doesn't make sense, bad game decision. People naturally want to enjoy their new jobs and experience them at their early stages and gain that sense of fulfillment, in the same time however they dont want to go through grind from scratch only to get an optimized version of a duplicate class counter-part, which is also a valid point.

So SE.. What real purpose or justification is there for having a job system in the game when you have a class system which is essentially the same?

Optimize for party play? Really? I really don't buy that.
The thought seems ridiculous to actually want to put in a significant amount of development and resources into a new job system including new mechanics, balance, purpose, quests, lore, creativity, etc.. all for the sake of optimizing party play. Not to mention the obvious fact that there are so many other issues the game is facing currently and could use more attention.

I mean since Class system is facing a complete overhaul with the intention to have it more unqiue and serve a purpose, why even bother with the job system? Abilities are already getting restricted to be class only, and all abilities will be revised and fixed up.
So what's the big idea?

Personally, only logical explanation i see is that new Dev team realized the Armory system fails in many aspects and is short sighted by Tanaka and have introduced the Job system which should have been there since the start, because simply it works as it did in the other FF's. The only prob is they are stuck with a playerbase who have multiple classes leveled at 50 who got used to their versatility and would be a hard decision for Yoshi to pull the trigger on the Class system with his 'i dont want to take anything away from players' attitude, which while i respect, can also hinder the game's real chance of succeeding. Some level of sacrifice is inevitable in the process of fixing this game up.

Job System pros:

1) More unique/satisfying
2) Serves a specific purpose
3) Works way better for party play
4) Can easily have subjob type system to keep some flexibility at a reasonable level.
5) Works better for casual play, rather than having to level all classes to play your role properly and be in demand/worthy enough for real content.

This is where i would like to agree with Lienn, i would like to think this may well possibly be a transitional state until version 2.0 comes where classes/lore will be phased out.

I hope it is, if not, i hope they come to their senses Asap before they dig themselves a bigger hole, and just come back to one system that addresses all the issues above.
i.e Remove classes in the wake of the job system.

Why have Monk when you Pugilist? or White Mage when you have Conjurer? or Paladin when you have Gladiator? or Warrior when you have Marauder?

Redundancy is really not good. Not for it's practicality, nor for the image of the game. Keep the game simple and meaningful.
Think FFT. I think a system similar to that would work best for this game.