I believe that SE should put time into making a great sword based class for FFXIV because I feel that the depth of the games combat is all be it exciting but lacking in diversity in terms of what to choose for classes. I also feel that a great sword class would help add to the roster of tanks that this game has to offer.
In final Fantasy Xi Dark knights are heavy weapon wielding damage dealers that rank up with warriors in terms of offensive power. If Dark Knights were to make a come back as a great sword class in FFXIV It would create a bit more variety for the DDs in this game.
Secondly Mystic Knights from the older Final Fantasys or Rune Fencers as they are called in FFXI are a great tanking class that would provide secondary options and more party strategies for players.
With a game that predetermines your job roll I can only hope that more jobs to fill rolls will surface in the future. I believe that SE could implement this class similar to the mage classes that open up multiple high tier jobs at the same time.
Shadedonyx.