Interesting how this evolved from "what is rdm all about" to "what rdm should be all about based on past iterations."
I could say what rdm used to be all about, but after 75 cap raise it all changed. Now people are doing what ever they can to keep rdm afloat in some way given what SE has done by introducing enfeeble immunities en-mass, while introducing spell lines that only augment the rdm attributes and functions. The few spells they allowed rdm to have as a new enfeeble, they then slapped over to whm, blm, or even drk to use thus once again putting it off on the sidelines.
As other say, this pretty much translates to "Rdm is in a weird spot of no endgame utility" and it is mainly due to SE this time rather than the play-style of the player base. The only A+ Skill rdm has is kicked in the face due to coded immunities or constantly sees new spells being passed off to other jobs that have better utility. The ability to buff is better left to cor, whm, brd, or Sch....because of better utility reasons also. DD is lack luster in comparison to real DD jobs in both Melee or magical venues. So, with a job that once had significant endgame utility, rdm has now become the oddman out only called on if the more useful job isn't an option.
As for the side discussion of what rdm is vs what rdm was, both side have substantial merit in their arguments. Yes this is a later iteration of a franchise, but it is also the first one of the franchise that became an MMO. For the most part, it is vastly based off the past iterations of which the job class originated from, but rebalanced with the MMO mechanics in mind which are constantly under development and balancing. Unfortunately, rdm at this time is in the need for some sort of balancing to bring it back to life, but I don't expect to see this until sometime after lvl 99 cap and tier 3 merit groups are added.