It is true that Cras used to be all over the place, Enis and Enus always will be since their advantages to any group are pretty apparent. Same goes for Pandas if people caught a glimpse on real end game.
However there are incredibly powerful classes that are not merely represented enough among the playerbase. Xelors are one of them, but even more so Rogues.
Fire Rogues are the most ridiculous thing for any kind of dungeon crawling and "normal" fights this game has seen in a while. You can just take 2 of them to ambassador dungeon and you are fine. Doesn't even matter who else is in the group.
At UBs fire rogues have very limited use, but here earth Rogues start to shine. There are some really funny strategies involving fussilade floating around.
What I want to say is that the current distribution of chars played probably doesn't reflect the actual power levels, but in a way it is a good thing that the power of certain classes is not so obvious to everyone.