tbh OP, it's incredibly easy to gear up for the content you are playing now *looks at Ironworks gear*. What you are doing now is incredibly stupid and stubborn, crudely put.

That said, I have no issues with undergeared tanks if they put in some sort of effort (I run into those types often), as long as you know the priority targets.

Edit:
Actually, I ran into this Dark Knight the other day in Cutter's Cry when I was helping my gf leveling her White Mage (I was there for light for my Artemis Bow). Other DPS was a Bard as well. Somewhat properly geared (weapon was a bit weak for the dungeon, at lvl34 I think), but otherwise seemed fine. First pulls, everything was fine (those ants die fast anyway). Then we run into the first Bomb-type enemies. This is where I noticed something: the DRK only used Unleash once on a group, picked a target, then started to use the enmity combo *only on that target* (which was not one of the Bombs)! I attack the Bomb, along with the other Bard (he was a chill guy, even asked me for some advice since he noticed I was a lvl60). I pull aggro. Tank starts bitching like I killed a puppy or something. We finished the run, but needless to say that tank pissed me off.

tldr; Tank didn't do his job properly and was slightly undergeared.

Don't turn into one of those tanks, we've already got enough of them as it is.