My deal breaker was similar, in some ways. I still hold a lot of hope for the game and log in from time to time, but I rarely play for sustained periods.
Like you, I started up and found everything beautiful. I was feeling the magic and I was psyched. Unfortunately it faded quickly; I explored every corner of Ul'Dah and spoke to every single NPC in the town. The lack of quests and things to do contributed to the magic fading. I did the story line quests as far as I could for my level; I actually really enjoyed them, but they went by too quick and than there was nothing to do in between until you could unlock the next set. Well, except for grind. And grind I did. Now, I'm not complaining about the grind itself, because I think we level ridiculously fast in FFXIV, but it's just the monotony. I've soloed every bit of the way, save for maybe 6 behests. There's just not really a need for a party and I wouldn't know how to get one if I wanted one.
Ultimately, all the solo play became boring and repetitive. My actions don't feel like they carry much wait and I personally find the combat system leads to an excess of button mashing. I understand how to play with different strategies and I don't find the combat entirely boring or repetitive, but the different skills are very interchangeable for me and the abilities don't carry as much weight. The interchangeability of the skills and the need to keep hitting the basic attack button make me feel like I'm just spamming a lot of skills over and over.
There isn't anything that feels the same as using Berserk than using Soul Eater than using a WS, for example, or like using Sneak Attack, using Trick Attack and than timing the WS to fire before the effect is wasted on a regular attack. There's nothing that feels like timing Utsusemi or even as important as using meditate (even though there are ways to boost TP). The abilities just feel empty, which means that the combat is less exciting, and when you're doing a lot of soloing and not coordinating/socializing in a party, there's nothing to supplement that empty feeling either.
This, on top of other systems that just aren't up to snuff - I'm not saying horrible, just not what they should be. For example, the new market wards aren't too bad, but I still like the old AH system SO MUCH better. I used to just sort everything by level and shopping was a breeze. The search feature is another example, and contributes to why I wouldn't know how to find a party if I wanted to. I don't want to sit in town and try to find people who are looking to group; I want to put my flag up, make a search comment and go out and solo while I look for an invite. Yes, we level faster in FFXIV, but getting to level 20 on a couple of combat classes without ever joining a party just feels odd to me; by this time in XI I'd have been in several.
Another thing that really doesn't work for me is the lack of new zones to explore. In FFXI I started in Gustaberg. By level 10 I was in Konstacht Highlands, assuming I hadn't errantly wandered into Dangruf Wadi or Palborough Mines. By level 13 or so I was getting my first invites to Valkurm Dunes, and there was a possibility that I'd accidentally wandered into Gusgen Mines or Pashow Marshland. And all of these places were distinct and different and it made the game exciting. And they all had different monsters. Where's the mob variety? Everywhere I go the name of the rats just changes (hyperbole, yes I've seen a decent variety of mobs, but nowhere near as varied and exciting as FFXI was). Also, the roaming NMs like Valkurm Emperor and Leaping Lizzy, for low levels.
Overall, the story is, I was impressed to start, but the magic fades quickly and once it does, there's not enough substance to ... sustain. I still have high hopes that they'll improve the game, so I'm patiently waiting and still log in every once in a while when I'm bored. Right now though, the game just doesn't have that pull I'm looking for.