I doubt anyone else shares this opinion, but having been on both sides of this thinking (or lack thereof) I kind of prefer XI's lack of "proper" balancing. I was one of those people who was terrible at XI and ALWAYS played the mentioned top classes, but if you check simulationcraft, even on WoW there's a test dummy difference of like 10-15% between the best few and worst few specs. And that's with almost constant tuning and retuning and basically changing classes completely between major patches. Even worse is the expectation that all of these be absolutely equal so when, for instance, Heroic Ragnaros falls you get a swarm of idiots yelling about x class y spec being completely worthless because they weren't in the raid comp for the world first kill.
To be really immune to this you'd literally have to level 5 characters (and rep with all of them, and level professions, etc.) - BUT AT LEAST THEY MADE LEVELING SO EASY NOW YOU CAN DO IT IN A DAY! Not that I would know, no siree! At least on XI if you truly cared about that difference you could level one job and be pretty much set for the rest of the game's existence. As long as that job wasn't SMN, teehee!
How tightly wound WoW is also sort of takes out any necessity for real experimentation. I stopped playing during ToAU *disclaimer*or whatever it was called, but I remember main tanks going from PLD/WAR to NIN/WAR to PLD/NIN and NIN/DRK in my LS (I even got a chance to do the hilarious NIN/BRD before they nerfed that runspeed song). In the same regard, RNGs got nerfed to hell for some reason, and then by next year melee classes were doing far more than RNGs ever could. Despite there being nearly no relevant changes to any of those jobs' mechanics (after all, we were wearing Zilart gear through CoP right!) and the standard way to do Kirin went from 2 hour kites to 10 minute burns simply because of people playing with the game in the background.
Also, for better or worse, I never felt that the player base got punished for breaking the game as long as stuff wasn't completely going wonkers. There are plenty of other things wrong with what I said up there and with XI in general, but I don't think that having a game very loosely tuned so that odd ideas are rewarded - especially when a large amount of cross-class swip-swapping is intentionally how you're supposed to play - is necessarily a bad thing.
XI Wiki



