It worked great in FFXI because gear in that game worked fundamentally differently compared to modern day MMOs (gear swaps + horizontal gear progression). However, FFXIV's item progression is similar to WoW's and is vertical progression, so at some point your older playerbase will simply stop running older content because the items won't be of any use to them anymore (in contrast to people in FFXI still running Sky even years later for stuff like Haidate).

I loved FFXI's item progression but I just don't see it happening in this game. They have to either rehaul how stuff works in this game or eventually raise the level cap.