I see what your saying, MRD could benefit more by having all the stated skill available. I would say that this is an option for those who want to just hold a lance. I personally got this game to be a DRG, but seeing how that is the same as a LNC, and the jumps kinda suck. I'm just trying to maximize this class.
About the MRD though, don't they really need to become WARs for the tanking ability? If they just stay MRD then they lose out on wrath and the benefits from those skills. If a MRD did this, they would still have to join dungeons as a tank, but it would seem they would have major issues holding aggro, unless they were geared to the teeth, like full Allagan or Allagan with Hero accessories. That's just my thought, I am currently only a 20 MRD looking to become a WAR. T.T