You get 6 leves a day FYI, 3 every 12 hours. Also, your claim is very anecdotal. It's not sustainable for you in regards to leveling multiple DoW/M classes but not everyone has this wish. I've been playing since beta and since launch I've only leveled two jobs, 4 crafter classes and 1 gathering class. A game doesn't become unsustainable because a gamer isn't happy with the avenues provided to level all classes.