Hopefully the idea of playing a jack-of-all-trades in Final Fantasy XIV is appealing, because you might not have any choice.
Final Fantasy XIV has a fairly unique setup when it comes to gaining experience: If you play any single class for too long, the number of experience points you gain will start to drop, eventually dwindling away to nothing. This is something that dedicated fans of the game have been angry about for a while, but it's only now that the game's director. Nobuaki Komoto, has explained why it uses such an unusual system.
Komoto says the reason there is a time limit - which is only eight hours long - on accumulating XP for each character class is so that players with more time on their hands don't gain an advantage over those whose time is more limited. He said it was part of the way that the game is balanced, and compared the system to real world fatigue, saying that it was unrealistic for someone to be able to train indefinitely.
It seems an odd choice to bring realism into the discussion. Even ignoring the fact that we're talking about a fantasy MMOG, having to swap to training as a sorcerer or a blacksmith because you've gone over your allotted warrior training time is not a realistic system. The fact of the matter is that a character in Final Fantasy XIV can train indefinitely, just not at the same job all the time. It's not going to stop hardcore players from gaining an advantage over the casual players either. They may level up in a particular class at a similar speed, but the hardcore player will be more versatile and flexible, because he or she will have training in a wider range of classes.
Final Fantasy XIV is released on September 30th for PC, and early 2011 for PS3.