They don't know what they want. Not at all. The same syndrome with people who cried for years they wanted innovation in the MMO genre, and then showed no interest in MMORPGs that tried to innovate. The devs know the safe cut and dry method is the way to go.
The best part is these devs come out with content faster than pretty much any other MMO's dev team and the complaints are still rabid. People are just insatiable.
I suppose the one thing they could do is make content that is fun to repeat over and over. I know when I used to PvP in MMOs I'd have fun playing even the same three battlegrounds over and over because the way enemy players fight is unique every time, so PvP is content that doesn't lose its fun factor. If they improved the PvP as much as they could, that may help.
As far as PvE content goes? I have no friggin clue man. Fighting scripted mobs is only fun for so long, no matter how difficult those mobs are. They just can't be designed fast enough to satisfy the content gluttons. This isn't a problem of just FFXIV, in fact other MMOs who come out with content slower have it worse. Make no mistake, pretty much EVERY MMO takes longer to come out with content than this game. So at this point these people's complaints are not with the game but with the genre itself. THIS is what a theme park MMO is.
Make the fights too difficult and the casuals complain and moan about the difficulty, and become demoralized and eventually bored. Make it too easy and THIS happens. There really is just no good answer to combat this issue. This black hole of content people claims exists in fact didn't exist in older MMOs because everything took longer to do. They artificially extended your time. Now with the modern MMO's focus on accessibility, devs can't make content fast enough, no matter how good they are at their job, no matter how passionate and hard working they are.
For all you people claiming you want innovation, please, by all means, let's hear your amazing and innovative suggestions that would solve the problems the MMO genre has been plagued with for years.
PvE encounters intrinsically have no replay value once you figure out the mechanics and how to beat them. This would be no different in any other MMO you play, it's just the nature of PvE...
Only things that extend lasting appeal in PvE type single player games is adding better armor/weapons, collectibles, costumes, and achievements. Interestingly enough, FFXIV has all of this as well.
Most of this thread just screams to me of entitled gamers demanding things having no idea how to make things better or what they are talking about.