My WHM and My PLD are geared just fine and my DRG is well on it's way to the same level of gearedness. Just because you can't deck out every class in af2 in few months does not mean you can't be optimal on them. There is DL gear which is ilvl 70 and is good enough for almost all content on all jobs. there is Crystal Tower coming which will drop ilvl 80 gear and again will be good for all content currently in game and for all jobs. You can get a relic for each class aswell which all of the above can and will be farmable at the same speed if not faster than doing it on a seperate character.

Even in games like WoW I geared multiple characters almost at the same time but there was always ONE that was a few steps ahead of the pack because i spent more time on that character. The same concept applies in this game except you are on a single character and are now gated by a cap instead of a time/character blockade.