Turning DRK into a tank was a huge mistake.

[Duelle]

You're wrong OP.

1) Dark Knight was only "DPS" in FFXI. In FFIV and all other FF games that it appears, it's a "tank" job.
2) Bad tanks are bad tanks. It doesn't matter which tank job they choose.

A job known to sacrifice HP to deal damage is a tank? >.>

There's a reason a number of people expected the job to enter the game as a DPS before the announcement was made. The only real analogue in FF to a tank for DRK was, surprisingly, Gafgarion from FF Tactics (because Night Sword drains allowed him to outlast pretty much everyone).

To FFXIV's credit, this is basically a brand new rendition of DRK (none of the other versions focused on the "harnessing the dark power" thing). It is understandably jarring, in a way. Sort of like if SE announced that the new tank job in 4.0 is Calculator. You'd definitely have people going "WTF?!" over that.