A little maturity goes a long way, pouting because "I didn't get what I wanted right away!" is nonsensical.
You'd easily think "Oh, it can't be that hard to just do it, surely they'd have it done by now" but consider the bigger picture.
Arcanist {As well as SCH/SMN} were rather rushed.
The development for ARR in general got a little heated and rushed at times too on release ontop of all the problems faced on launch pushing back content (2.1 was a catchup patch mostly).
There simply wasn't any time to add in any other classes/job at the time.
"But the patches in the original launch...?"
From the get-go the game was destined to be a disaster and the team knew it after only a short period of time, as did the entire company. So when the new development team came in to try and fix the mess the last thing that was coming to mind was;
"Hey guys, lets get started on Musketeer, we have no real game to work from here but MUSKETEER GUYS!"
Even the original development team wanted; Fencer, Arcanist, Mystic, Musketeer, Shepard (etc) for the original launch, which (due to their strange and slow development cycle) never came to be as you already know.
Remaking almost the entire game from the ground up in a period of two years. Everything took a considerable chunk of their time, thankfully they were able to take the time to cobble together (It sadly is very cobbled together) a new class and two new jobs for something to level for new/old players.
Developing a new class/job can make or break a system, it takes a considerable amount of planning, adjusting and tweaking and not to even mention testing (which is assumable at the moment that no part(s) of the development team have the time to do so in time for 2.2)
A short list of things to do for adding a new class (I've left tons out I'm sure);
•2D/3D Models (Weapons, AF Gear, Relics, Class/Job Specific Weapons 1>50+),
•Unique Roe/Norm/Lala Animations,
•A metric ton of Sounds,
•Statistic balancing,
•Class Role Type,
•Overall Job Role
•Overall Damage Output,
•Overall Battle Dynamics,
•Ability Planning/Prototyping/Adjusting/Implementation/Testing,
•A lot of Class>Job Quests 1>50+, )
•Lots of new Cut scenes and NPC(s to develop and write up dialogue for,
•Loot Table adjustment across the entire field,
•Battle Balancing (does the new job affect the tide of current battles?),
•Q/A Testing,
•Finalising Graphics/Animations/Sounds,
•Bug-testing/squashing
•Releasing so Bakiraka doesn't un-subscribe!
And much much more all of which can take a really really really long time to produce.
TL;DR - The development team simply didn't have time so far to make this class happen, there's been delays, content rush panics, deadlines, new game content and fixes left right and centre to worry about. Musketeer will come out just not yet. Bear in mind and remember that the game was behind schedule on launch and that'll have a knock back effect probably up to the first expansion before the rippled effects are recovered from.
I could be wrong however and they'll suddenly reveal it on March 21st (I doubt it however)
Correct! (For 2.2 it would've been in the press media kit though to build hype).
So I'd wager 2.3, seeing as 2.2 is a pretty hefty end-game content patch as well as developing the main story further.
Hopefully Musketeer and (whatever else) in 2.3 is enough to tide us over till the expansion.