The first five of the expanion's eight chapters were the only missions included with the initial expansion release, and most of the new zones that were accessible at that point in the story had very few Notorious Monsters until a few months later, yet despite the fact that there was nothing for a character to gain from these missions, people were doing them.
Chapter six wasn't released until the expansion had been out for a month. It included the most difficult single-party battle in the game for its time, and arguably the most difficult mission in the game at its time (only comparable to the archangels when done as an alliance battle). Despite the difficulty of the missions, this chapter offered no reward at all, not even in the form of a new zone to explore. Yet people were doing it.
Chapter seven, which rewards you with Sea access, wasn't released until four more months had passed. However, when Sea was first released, it was only released because the final battle and mission of chapter seven needed to dump you there for the story's sake. The exterior portion of the zone was therefore all that was available at the time. This means that its chain of HNMs was inaccessible to farm, since the interior portion of Sea hadn't been added yet. It was a fairly pointless zone seeing how its only purpose was to be an exit to a battle, with the only incentive for players being its story relevance and new sights to see, yet people were still doing these missions.
The interior portion of Sea wasn't released for another two months, meaning the discovery of the Sea HNM chain wasn't until a whopping seven months had passed since the first Promathia mission. Then it was still another three months before the eighth chapter of the expansion was finally made available in Sea, so it was a total of ten months before the expansion's rings were even discovered by players. Then it was still three more months until Limbus was released, clocking it at thirteen months after players started the first Promathia mission. I hate to say it, but your argument is invalid. If these are the only things that players were doing the Promathia missions for, then why were there players logging out in Tavnazian Safehold on the morning of the chapter six patch, eager to see what the next mission would have in store for them when they next logged in? Those were players who love a good story, and Promathia delivered one of the most memorable stories and engrossing stories in MMO history. Why were players banging their heads on desks to beat the infamous airship battle at a time when there was absolutely nothing to gain from doing Promathia missions? Those were players who enjoyed a well-crafted challenge simply because of the rush that comes with a hard-earned victory, and Promathia certainly delivered for them. Why were there always others like myself running around in Sea at the end of chapter seven, during the period when only the exterior of the zone was available and it was just a pretty place to grind merit points in? Those were players who could appreciate things as simple as having new worlds to explore and new sights to get lost in, and Promathia delivered for them too. Many of these people are now playing FFXIV in hopes that the company who delivered to them once before will be able to do so again, especially now that they're reaching out and building a game based on players' input. The experience of Promathia-era FFXI is what a large portion of FFXIV's community seems to be looking for again. The other types of players, who play games purely to improve a virtual reflection of themselves, have already found a place to call home in games like WoW and SWtOR.
As for arguments that the missions were too difficult and required specific setups, I have to beg to differ. My static party included a Paladin tank, a Galka bard, a White Mage (me), one Summoner, one Monk, and a red mage who still hadn't reached max level before we finished the final mission. (Read: no Utsusemi or Eagle Eye Shot). The fight immediately before the final encounter took us several tries, and I believe we wiped to the airship battle about five times, but we were still able to progress through the missions as they were being released (read: pre-nerfs).
Yes, it was difficult to find a group for the missions. As I just mentioned, I ran them with a static. (I will also agree with the poster who mentioned that many of the fond memories of Promathia could be attributed in part to the bonds it created with the new static friends that they were forced into making along the way. It wouldn't have been nearly as exciting to defeat those encounters with pick-up groups, and you really learn to function as a well-oiled machine over time. There's something fun about playing with players who you know so well that you can practically read their mind.) If you didn't have a static, you simply weren't going to find groups for the later missions. However, I don't attribute this to the community not wanting to help their peers catch up. I attribute this instead to the amount of time that each mission required all party members to commit, and the fact that all party members needed to be progressed at least as far as that same mission in the story. Not only did each mission involve a good hour of sneaking through large zones full of difficult mobs, but many of them existed in remote places that took a long time to travel to, and involved several hours of farming items such as Mistmelts and Liquids, which could not be farmed solo and were needed by all party members.
I don't think we have to worry about this with FFXIV's current dev team though. They're already showing us that they know what was wrong with FFXI. Right now in FFXIV you can say, "Hey linkshell friends, can some of you please help me with my Warrior AF fight? It's just a little west of Uldah, so we won't need to run for more than five minutes to get there, and if you still don't want to spend the time running there then I can even Teleport us there (without having to have WHM leveled) and you then can immediately Return yourself back to town or your most recent leveling spot for free when we're done. Once we gather together, we immediately find ourselves facing a single fight and that's it, we're done. You don't have to have the quest active or completed to help, and you can be back to what you were doing in just fifteen minutes." To those of you who are saying that you've been having the same problems finding a party for things like AF in this game as you did for Promathia missions in FFXI, then I really have a hard time believing it. You CAN find a party for your AF in this game if you ask around, without ever having to spend six months meeting a static for four hours a day, three days a week. The game just doesn't do it for you like other games do, so you actually get a sense of community on your server by getting to know the people who are usually online during your playtime hours as you regularly find yourself helping each other. (Even WoW's developers have openly admitted that WoW lost much of its sense of community as soon as they implemented cross-server group finding.) You can't blame the developers of FFXIV for your trouble finding a party, because they've eliminated FFXI-scale time requirements (reducing mission length and, in case of wipes, ability cooldowns, while removing pre-mission item farming), eliminated restrictions on who is eligible to help with quests/missions, and eliminated class-specific teleports, not to mention that this game has a dozen times more teleport points to get you where you want to go when compared to the small handful that existed in XI. They've made it easy for players to help each other.
Before that leads anyone else to say that players will only help with things if there's something in it for them, even when it's as easy to help each other as it is in FFXIV, let me stop you now. I know MANY players who contradict that statement, with my entire linkshell for example dedicating every other day to what they call "Help Your LS Mates Day." If you honestly think that players don't want to help each other in an MMO, then either you're that type of player and you simply assume that everyone else is the same as you, or you need to ditch the folks that you've been trying to count on and then find yourself a new, quality linkshell full of helpful players. They're out there, I promise. MMOs wouldn't even exist if there weren't other players out there wanting to help their friends and play together. With the exception of full AV/CC runs (their hour-long time commitment being the longest that this game has, and a lot to ask for in today's busy world of responsible adult gamers), you shouldn't be having ANY trouble putting a group together for full-party content in this game. If you make any effort at all to associate yourself with the right people in this game, you should be finishing most party-required quests that you set out to do within thirty minutes of deciding to look for a group for them.
Now, for those saying that level caps are lazy ways to add artificial difficulty to encounters, that's just not true. Some players enjoy being thrown into new situations that require them to survive with only a limited number of abilities, instead of the same abilities that they use a million times every day. Blowing things up with max level abilities and pimped out gear is fun for a couple of hours, but MacGyver wouldn't have been on the air for as long as it was if its hero was just a guy running around with a machine gun in every episode. Being allowed different configurations of resources is definitely a valid way to keep things fresh and exciting. Besides, the encounters were still involving new enemy models, and required solid group coordination. Do you remember the first Mammet fight? DPS and support players were taking turns juggling slows and binds on multiple mobs. You also had to keep an eye on the weapons that the mobs were switching between, saving different abilities to give you an opportunity to adapt to any increases in their damage outputs or attack speeds. Meanwhile you had to tank one mob at a time far away from the rest of the group, because each one of the mobs shared a percentage of the enmity that was generated on them with other nearby mobs, meaning communication was required for heals between the split party. The level cap was an added challenge, but far from the only challenge, or even the main challenge. The vast majority of the expansion's encounters were far from your typical tank and spank, and the level caps were anything but a lazy way for the devs to cover up this shamefully alleged lack of creativity.
All that said, I feel like I encountered a flaw with the Promathia missions that hasn't been mentioned here yet, and it stemmed from the level caps, but the problem was not the experience of playing with level caps themselves. What bothered me was that they were essentially providing low level players with story content that was meant to take place after playing through the Rise of the Zilart story. It was heavy with references to Zilart and Kuluu history, let alone the fact that the Kuluu even existed in the first place, and if you hadn't played through Rise of the Zilart's story missions, you'd find yourself pretty lost in what the NPCs were talking about from time to time. The level caps provided a fine challenge, and low level players did indeed need some content to break up the long tedium of grinding in that game, but unfortunately it created a sense of unevenness in the story if it was started before a player had reached the level cap.