Firstly, yes, this character is an alternate. Actually, it's not even an alternate - I quit for a period of time from late 2.x to late 3.x. When I returned, I created a new character on a new server, as many of my friends had migrated. I didn't update my Forum avatar, however.
Secondly, from my perspective, there actually hasn't been much that changed since 2.0. Letme run through the list of examples you brought up, because I think it's a decent case study.
- Cross Job Stuff: These really didn't change in a way that enriched the game experience. We no longer had to level other jobs to access cross-job abilities, but that actually removed content rather than added anything. The abilities added, with few exceptions, were not functionally different from anything else that existed before. Rescue is one counter-example, though due to how the game is balanced, it certainly doesn't have any real use outside of maybe Savage / Ultimate content where AoE can actually kill you in a hurry. Beyond being irritated that most of my 'role' abilities were yanked from what I used to have natively (I play WHM), it didn't change the experience of the game in any way that I noticed even half an hour later.
- Dungeons: I'd argue these haven't been changed at all since 2.0. There are new coats of paint and a handful of new mechanics, but Hells' Lid and Fractal (Hard) don't play any differently than Amdapor Keep and Wanderer's Palace did back in 2.0 (beyond being significantly easier). Similar conclusions are reached if we extend this study to Trials, or Raids. The primary issue here is that new mechanics simply don't alter much beyond one's movement patterns, which is a very trivial change. If new mechanics dramatically altered how one played their job throughout the fight - Abyssea's proc system is a good example - this would be a non-issue. Alas, though, this isn't the case.
- Housing: This one's new, I'll give you that. And it's a fantastic addition, even taking into account all of the numerous implementation issues. We need more broad expansions of content like Housing.
- Gear: I really don't think gear has changed at all. It changes nothing but the damage we can output and take. Where are the items like the AF sets in FFXI, which actually altered the behaviour of some abilities? What about items like Scorpion Harness, that noticeably alter your ability to perform certain party roles like shadow-tanking? There are none, and that's a missed opportunity.
To dive further into your Eureka example, I agree that a lot of people pre-judged the content. That said, so did SE: they pre-judged it so badly, in fact, that they didn't appear to have anticipated the formation of FATE trains (the content is clearly not balanced or designed around them), which is almost an unforgivably bad fuck-up. It's largely what killed off the potential Eureka had to alter a different experience, actually: the key difference between Eureka and non-Eureka was XPing via party camps. Between the FATE train imbalance and the lack of a Level Sync, however, it's almost impossible to experience the content as intended, and get a truly different feel from what FFXIV typically offers. That's a shame. I'm hoping they rectify it in the 4.3x Eureka content, but it's hard to say.
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As a wrap-up point, and I speak further on this below, the fundamental issue I have is that FFXIV naturally demotivates people to play it. Nobody can repeat the same tasks, indefinitely, without eventually getting bored. In single-player games this isn't a problem, but in MMOs (and in sequels, actually), it's incumbent upon developers to continually change and refine the product so as to offer a continually-engaging experience. I think SE has done well at this around the edges of FFXIV; they've done a great job designing difficult, creative end-game fights, and they've done a great job expanding the non-Job content for more casual players (Gold Saucer, Housing, Triple Triad, etc.). Core elements of the game, however - crafting, gathering, non-extreme combat, the tools available for socializing - really haven't changed much since 2.0. That means players like myself are finding it harder and harder to find the motivation to re-sub. It's nothing to do with not enjoying FFXIV, and everything to do with having enjoyed essentially the same formula for multiple years running. It's getting stale.
And I still think the development team is allergic to change. It wasn't intended to be an argument, so much as an observation. When it's possible to predict 95% of an update cycle a year in advance, you aren't being creative enough, in my opinion.
FFXI with the ToAU XP camp changes and Abyssea content; Guild Wars 2 with their well-thought-out Mount design; World of Warcraft with Cataclysm and large-scale skill tree changes; EVE Online with the Phoebe update. Each of these things mentioned more dramatically altered how everyday activities played out in the world than anything FFXIV has introduced since the reboot.
Getting more in-depth, let's just study FFXI, which is the title I have the most experience with. Zilart increased the level cap dramatically, and greatly expanded the variety of activities available at cap. CoP didn't massively shake things up, but ToAU did, completely altering the established XP camp dynamic and introduced Nyzul Isle, Salvage, and Assault, all of which offered distinctly fresh styles of play. Abyssea a few years later again completely shook everything up, with a massive level cap increase and indirect impact on how XP was gained, along with very unique play and capabilities within Abyssea itself.
Again, FFXIV has none of these things. There is nothing in FFXIV that meaningfully alters how I play my job except PvP or being in capped content. Group size doesn't really impact it; fight mechanics don't really impact it; type of content doesn't really impact it. Rotations retain much of the same feel they had in 2.x, even, albeit maybe with different abilities swapped in. There is one job-specific exception to this - Bard - but SE hasn't been similarly creative with anything else.
This is of course true, but the game is still the appropriate source of blame here. You're conflating the motivating factors behind why someone plays in the first place (which vary tremendously), and why someone loses motivation to continue playing. I'll admit I wasn't very clear on this distinction myself, but I felt it was implied in the context of the OP.
If someone loses motivation to continue playing, then unless there was some ground-breaking life event that altered their motivating factors significantly, the game effectively failed to retain a customer. As with all areas of commerce, the blame for this should fall upon the product. After all, an existing player has already demonstrated a motivating factor to play in the first place: they might be advancement focused, or motivated by discovery, or enjoying socializing, but there's
something that caused them to play and enjoy themselves in the first place.
Your articles actually do more to prove my point than yours (and thank you for them, by the way - interesting reads, both). Consider, for example, someone interested in advancement, which the OP implied is one of their motivating factors: FFXIV fails spectacularly at offering a real sense of advancement in terms of character power. It is too visibly a hamster wheel, running constantly just to keep pace. One's achievements in this realm are short-lived. This was a design decision, made by the FFXIV team, that actively impedes their ability to motivate players who are advancement-focused in the long term.
Similarly, let's look at players who are motivated by the social aspect of MMOs. SE has done nothing - absolutely nothing - to foster or encourage lasting relationships between players. Combat is fast enough that it's difficult to form connections in dungeons, and even if you do, there's still - to this day - no ability to maintain a connection to them unless they happen to be on your server (although this is changing in the near future). There's nothing at all in terms of content that has any sort of social objective. There's no ability to search server-wide for Linkshells based on desired criteria. The net result of this? When the community a player is in slowly starts to decay, it can be very daunting to find a new one. If these players become unmotivated to continue playing, it is again, squarely SE's fault: they've done nothing to help out.
Again, I agree with your underlying point about players changing. But the OP, and many, many players criticizing SE on the forums - myself among them - have not gone through a life-altering change in the past four years. We've simply gotten bored. And that is not something that should happen, particularly in such large numbers, if the development team is doing its job right.