So let's say SE didn't name it "rogue"....and they named it Thief

People would still be angry and complaining because thief would then be a base class and "OMG thief has to be a job, it cannot be a base class!!!"

If it feels like a thief, plays like a thief, has the traditional skills of a thief, then is a thief even if they name it burglar or robber...what's the difference? the name?
Then you care more for the name than the playstyle? They could throw you a thief healer and would be happy because is a "thief"?

When it gets to 30 and becomes a NIN..it will still have the thief playstyle...PLD still plays like GLD, DGN still plays like LCN, WHM still plays like CNJ....but then again the problem is the name? feels like a thief, plays like a thief, has thief traditional skills....but is named NIN and has 5 new skills?