I think we're seeing with DRK the same thing that happened with MNK post-SB. As the poster boy, everybody played the job and to the devs, when everyone is playing the job, they see no reason to look at it or fix it.
I have a feeling it is going to get a patch style rework this time after they reworked it from SB. I think with a few tweaks to the kit and maybe adding in some old skills, they could really make DRK unique. They just need a mass exodus from the job which is going to happen since the other three tanks are so much more than what DRK is currently.