Okay, before people get irritated that I'm bringing up FFXI hear me out.
Among the complaints of "ded gaem" (dead game) between patches, would it be a good idea to put in a way to earn points to enhance our jobs?
Even after hitting level 60, you could still earn exp and say 1,500,000 exp = 1 merit point.
You could then allot it to improve the jobs skills by a small percentage. For example:
For MNK, each merit point into "Greased lightning" will increase the duration by one second for a total of five seconds maximum.
Or say MCH, each merit point into "Turret Damage" will increase damage dealt by turrets by 5% for a total of 25% when upgraded fully.
It doesn't have to be related to skills for job, but can affect stats as well like "Curing potency" for healers, Defense for tanks, STR, DEX, MND, Critical Hit, etc.
This way there would be something for players to work on between patches who complain that there is nothing to do. It would also breathe life into dungeons (in theory), beast tribe dailies, fates, etc.