You are dead silly if you think FFXIV flopped because the game was trying to be casual; if ANYTHING the game is far more casual now than it was at launch. Rested EXP bonus that is far superior to the utter-crap system that was Guardian's Aspect? Increased EXP through leve's and the implementation of power-leveling? Whether you argue PLing was intentional or not, the dev's seemed neutral about it to the point that it still exists today.
AF armor is far more accessible in this game than it was in XI; if you played during NA launch you practically had to beg high level Japanese players to help you finish it because lord knows your static party and LS was likely not strong enough to complete the body piece NM.
FFXIV flopped because the game was shipped incomplete that only a small percentage of PC users could even run; the PS3 version was not even done at the point (still isn't, arguably speaking) and alienated a good proportion of players. The UI was clunky, there was terrible server and input lag as well as possibly the worst implemented player market in the history of MMO's.
Once again, stop mistaking that long grinds, and tedious boredom equals to hardcore whereas simplicity must mean casual. I did 4 years of HNMLS in FFXI and at least 5 years of WoW raiding before my real life situation forced me into a less reliable schedule. There were a number of encounters in both that games that I could have said were challenging and also say they were easy.
People stuck with XI because of the people they made connections with and because of the terrible RNG (not ranger) system that made them kill Fafnir 97 times to get a Ridill, not because it was hard. Let's not count how many times (and hours of sleep lost) it took them even claim the HNM.
Don't believe me? You can still find the livejournals of plenty of these 'hardcore' FFXI raiders online. If you slowly go through their entries, you'll find that by the end--most of them agreed that the game just became a tedious job.