That could be said of any job in any FF. Just hand over what makes them unique to some other job.
I tried to make my version of Thief different by making them big on a few things.
I gave them great enmity control abilities, abilities to disable weaponskills on bosses and normal enemies, and even a time bomb that would make clearing stuff like the ants on the Princess fight easier.
Speaking of the Princess fight, the 3rd combo on the bleeding weaponskills, Cutthroat, would be invaluable against a boss of that nature. It'd be useful even against Darnus assuming the THF is good enough to apply the effect at the right time.
It's unique abilities like those that need to exist, and give purpose to jobs. If all thief had was Treasure Hunter, you'd be completely right, but if you read some of the abilities I wrote, if the job THF\NIN played anything like that, it'd be far from just another DD.
