Fates are fine. Eventually people will finish their first job and realize there are no other gear handouts to level subsequent jobs. Dungeons will become more viable as a path for gear and experience when they run out of quests. The only reason people are leveling so fast right now is that they are getting gear from quests and grand companies to supplement the exp that fates provide. After the first trip to 50 your choices are crafting, buying, or grinding dungeons for gear. Grand company gear is spread out well enough to force people into dungeons.