The issue with such content is trying to make it worthwhile, without causing strife in the community.
Like, what kind of progression would you even put?
You can't put gear becasue well, why bother spending 100 hours grinding out something equivalent to Tome gear? If you put upgrades to that gear then you'll get Savage Raiders annoyed that Casual Joe can get equal or better gear than they get for doing the hard content in the game.
If you don't put gear... Then there's no "Progression" for that job is there? I mean, unless you put in Materia that is better than grade VIII (But then you'll get a bunch of people complaining about how they need to grind so much for it).
To be honest, I don't think the issue is lack of "Progression" for jobs, but rather the lack of content for to use up to date jobs in. Once you're geared out in Normal/Tome gear what is left? EX, Savage and Ultimate. After that? Uhh...
Even doing side activities like farming FATEs for Shared FATE progress and Bicolour Gemstones ends up being meaningless for "Progression" due to ilevel syncs on everything that isn't the newest level 80 content anyway...
At best, you can hope for something like Eureka, where you can grind out for a shiny glamour (While for the time before you get it, you have little progression because lulilevelsync)
Edit:
This is generally the issue with using acquiring gear as the end-goal of "Progression". You get the gear and then... You've finished the game until the next content drops (That will likely be tuned to a lower ilevel than said gear, so people who don't have it can be on a level playing field, aside from say, Savage which will be tuned to the new crafted stuff which will be better than all the gear you farmed for making it ultimately pointless anyway)
Hence why the "Glamour is the true end-game" meme exists. Due to the irrelevancy of gear as nothing requires it outside progressing into Savage.