ragna helps newbies gaining some reputation, developing strategies, finding longterm battle survival forms for GW and is on new servers actually fun when there is a high density in population.
however, the further you get into the game, the more pointless it becomes for the individual players to the point where they stop signing up. it's one of those newbie things from the game as for example for example midweek madness is where the further you advance the more obsolete it becomes. with lady and heavens palace based on the rewards it's the same thing.
i think there is more important things that need to be changed in game than ragna.

that being said, the real problem of ragna is the reward system being antiquated. after introducing RC and the new title/reputation system, some rewards like royal arena got adjusted and gave you more reputation and others like HP, guild chest, etc ... and the "dead horse ragna" didnt. in my mind the developers simply forgot to adjust the ragna reward system at the time when the title system got changed.
the easiest fix would be to increase ragna rewards tenfold. so someone who does a 30 killing streak gets 20k reputation instead of 2k and 10m credits. 10m credits maybe sounds "too much" to some on the first thought but when you compare it with other events as for example banish, lady, HP, its spot on the point and a more average reward for an almost hour long daily event.