As long as I can eventually dual-wield pistols, I'm happy.
Bring on the Gunner job!
Anyways, FFXI operated on a class to job basis kinda. You levelled white mage i think it was, then you could become a summoner or something else, there's no reason this won't operate the same way, and that classes will be a base with which to build on lots and lots of different jobs. This game is only 1 year old, there's still a loooong way to go and it's too early to be picking apart the first small step in it's expansion, and once SE reach the 1.21 mark and/or the PS3 version is released they'll begin to focus more on where the game is going, rather than trying to fix/build up what it currently has.
The only thing I thought strange is if Thief is actually a job. I always imaged Thief would be a class which would then expand to things like Ninja, Assassin etc. jobs, the same as Pugilists could build to Monks, Martial Artists etc jobs.