The OP's concept is indeed a great comprise and a great way of looking to incorporate the thematic Final Fantasy staples into this game.
The great thing about it is that it still maintains a character's identity, without pigeon-holing them into a predefined role. Being a single job doesn't make anyone different form anyone else. It only makes someone identify with people who are exactly like them. Needing to be a job from the premise of wanting to be unique is a wash in light of the OP's system and even from the current system already in place.
How many people leveled Samurai after they gave them the two handed weapon buff in FFXI?
How many of those players who were playing Samurai had the same gear or were on their way to acquiring the same gear?
How many people leveled Red Mage or Bard after Treasures of Aht Urghan?
How many viable tanks were there?
How important was having a tank?
How many cookie cutter players played those jobs?
Every player is less unique in a strict class system ala FFXI or WoW. The only thing that differentiates a player from others is their name and accomplishments. They literally play the game like everyone else considering the limited options that are either available or viable. Cutting the armory stifles the options and tools necessary in which to think outside the box. Incorporating the OP's concepts provides the aesthetic and class uniqueness from those systems.
By going to a strict class system with locked gear and abilities, everyone loses the potential to fill open roles in a party whilst never gaining any true uniqueness.
Take the following scenario into account if the armory system is scrapped and a strict talent tree is put into place:
You are one of two mages in a party and you're currently spec'd to nuke. Your healer co-mage leaves because they have to attend to their children, go to work, don't feel like playing, etc. etc. You are now stuck looking for a healer ala FFXI or the alternative. In a strict class system with gear locks, you get to "go back to town". Not many pick up parties survive that venture, and it's useless time spent not playing the game.
In the current system, you can respec yourself on the fly and still fulfill that role if you need to. You can adapt to whatever party context in which you find yourself in, and do it on the fly. The downside is the stat distribution cool-downs. At the very least, they are too harsh if not completely unnecessary and make it borderline less convenient than switching jobs in XI, but even then there are workarounds through the stat trait guildmarks which must be earned.
Now I'd love a way to represent myself in a party too. Even better if I can do so in a way in which I can identify. I'm a fan of aesthetics and I'm also a fan to throwbacks from past Final Fantasy games. I'd love to wear armor to look like a Black Mage or a Dragoon. I'd love that gear to reflect my playstyle to boot, by giving me stats that support that role. I also want to have the title and familiar lore as well, but I need the flexibility that the current system offers now for when people with a life leave my party in the middle of a grinding session. I'd also like to create my own interpretation of that job by setting the abilities that I want, which would clearly differentiate me from everyone else.
As of right now, the armory system is better than the subjob system in XI. It's better than WoW trees. It's only lacking the aesthetic and stat distribution values reminiscent of a strict role system, but the OP provides a more than ample compromise.
On the concept of lore, your character has to start somewhere. Not only that, but implementing the classic jobs the way the OP recommends gives players a goal to work towards. In XI Balasiel required you to do three tasks before you could be a Paladin. While it was a pain for some to have to level another job when all they wanted to do was be a Paladin from the beginning, it still provided those who obtained it a sense of gratification for achieving that status. Not any rookie could just be a Paladin, you had to earn it. That made being a Paladin a greater accomplishment. Now just implement a similar system for every classic job and not only do you have your class uniqueness and nostalgia, but you can still be proud of any role you decide to pick because you had to earn it, much like AF in XI.
I know the term cookie cutter is thrown around a lot but I'm going to use it in a different fashion in order to represent what I think the OP is proposing.
The job system is a cookie cutter, the armory system is the dough. I can't eat cookie cutters and a bowl of cookie dough lacks the aesthetic appeal and flavor of a well baked cookie. My suggestion to the chefs is to use the tools available to them and finish the recipe through to it's completion.
Though I must say I've been known to snack on the cookie dough, and take great pleasure in doing so, while the chefs are cleaning their tools and prepping for the next step.
Like many of the respondents in this thread, I picked XIV, and to an extent XI, because of the flexibility of their systems and the attachment it created between my character and I. XI suffered a backlash from community pressures and XIV's system lacks the nostalgic reminiscence of other Final Fantasy games and fantasy MMOs in general.
I can't guarantee I'd stay if they scrap the armory. I believe the OP's proposal provides ample concessions to those who want the class uniqueness that is provided by other strict role systems. In terms of uniqueness, it differentiates both XIV and us from our respective peers while still providing the thematic elements that connect us.