As long as they make it fun, accessible for all, addictive, easy reward risk ratio, attainable content without the need of cheating and third party hack tools - then it's all good. They can and should revised some older contents and add more rewards to it. Some contents seems to be more popular to the japanese player base, for example: Walk of Echoes. They should make both empyrean via abyssea and walk of echoes identical since they are both about the same when it comes to completion time, with abyssea ones being much easier due to demands.