I have an answer but I am sure some or a lotta player would hate the answer. Now I will give the answer again, and I beleive that it will satisfy 2 things that players have been asking for. #1. The Devs use a point system, now everytime you run what ever it is you are given points, you are also given points for meeting certain requirements and that could be killing X amount of mobs, bosses etc. Some of you may not want to hear this but FFXI in some of the end game content had a point type system. Now after you have EARNED enough points players go to the coresponding NPC and trade said points for what ever it is they would like to get. Now I am not saying make the points too low nor too high, so I will clarify that right now. #2. The point system also gives players an idea of how close they are to getting what ever it is they are after. #3. This will benefit both casual and hardcore players alike, it also removes a horrid drop rate issues. Now again I amnot say get rid of drops altogether as there should be a place for those as well, example HNM's or world NM's whatever the Dev's wish to call them.
SE already has a point system in some end game in ffxi, as well as Wings of the Goddess for gear and such. There is no reason that the current DEV's could not use that idea or anything from FFXI. Now again I am not saying copy and paste, but take it improve it and use it. I do understand that they want time-sync's but that is where The dev's need to be creative about it. Lets look at the level 25 dungeon and the very 1st level 50 dungeon. Players are using them to farm seals (more the low level dungeon than anything else but still). That right there is a great way to keep the old content useable (seals do need some balancing btw). Another way to help keep players in running the old content (and I dont care if it is old or new) all gear drops can be turned into materia if the player so desired. Now if SE allows all the gear to be turned into materia, I am not saying make it meldable but if at least this gear is able to be turned into say some specific tpye of materia players would definitly want to do it. All that I have mentioned above could be done to add a time-sync as well as keeping the old content being used, it may not be for everone but it is a middle of the road type idea, because no1 can please everyone.