Personally, I'm glad that the base class for Ninja is called Rogue and not Thief. This is (almost) the best case scenario.

Why?

Because I would prefer something that is a traditional job in Final Fantasy series not be considered "just a class". That said, it falls a bit short of what I wanted. I was hoping we would get a Rogue base class, that branched off into the Thief job as well as the Ninja job. Some people might say "Well, in FF1 THF turned into NIN!" and yeah that's true, but FF1 also had "Red Wizards", etc. Also, since then, THF has turned into an iconic job all its own in the FF series.

I would still like it if the dev team would consider adding the actual Thief job in a later update. These could be Rogues who "went back to their roots" to become actual Thiefs (Thieves!) again. There are definitely a lot of hardcore THF fans, and I doubt they will be satisfied with NIN. Especially since there is no reason to ever play a class (outside of the once in a while a Warrior goes Marauder instead because dps). Someone who wanted to play THF wouldn't be able to just play Rogue in any actual content. You need to be on a job role for pretty much everything. The advantages in nearly all situations are overwhelming.

So, please consider (at a later time) adding THF to go along with NIN, side by side, as the 2 jobs that branch out of Rogue. I think THF could have a different enough play style to merit it, since they wouldn't use ninjutsu.