Point is though rones, is gives rdm a little something to do in their spare time to help the melees also, abit a small help, but help. And all jobs do get a little spare time, although rdm and brd less than others.
Besides haste spell there is really nothing else they can do to help the melees out minus the tank. Granted the sub is aimmed more at helping mages, but I also never cared much for convert ratio, I almost NEVER see rdms run out of mp so this is not a big issue.
I can never find rdms capable of hasting the whole frontline either(which is normally 3 people, nothing crazy), it seems people rate rdms on this board only based off how good they keep refresh on and how fast they dispel, and if they melee or not. But really...Haste is a pretty damn big deal.
Even in whm-rdm parties I'm always finding someone without haste on, noramlly me or the other DD, so that point is partly moot.
So if they're not going to use that extra mp to haste the melees when they have that extra mp, well at least/brd gives them something to do to the mages at the least.
By the way, on a 1-5 scale, whm,blm, and brd all have a 2 out of a 5 on HP. So any difference there is not worth mentioning. Although brd might have ever so slightly more.
