I'm hoping for a happy medium. I want to be able to solo, but I want partying to still be the preferred method. I want to be able to be self-reliant against small numbers of weak mobs for a little XP here and there when I don't have time, but I also want to be able to buckle down with a party for an hour or so and get some serious XP when that's what I want to do.

Problem with FFXI right now is that to do anything with a group you'd better set aside at least 3 hours of your life. It's just unreasonable.

I much prefer to solo, and once I reach endgame I tend to just reroll rather than play with other people.
With all due respect, there are other games out there for you if that's all you want from an MMO. To be honest, at the moment I'm playing like you. My wife and I are literally just grinding different jobs in FFXI for no apparent reason. We want a little FFXI flavor, but we don't want to be hardcore like we once were. Now FFXI has taken large steps to allow us to do this. Once upon a time it wouldn't have been an option. Soloing or duoing was a laughable idea. But with the Fields of Valor thing and lots of other small changes, it's more than reasonable.

The game has a good balance right now of allowing that casual play while still having a very hardcore end game. I don't want FFXIV to have that WoW feel where people can easily level a character to 80 in a month taking their time or a week if they aren't. I want levels to mean something the way they do in FFXI. I want there to be content all along the way. I don't want the WoW things where because it's so easy to get to 80, the only content that matters is at 80. I want my gear to matter while I'm leveling up and not replaced in a few hours of solo grinding.

But hidden away in caves and caverns and all sorts of dark, distant places should be danger and treasure. I'm not talking about taking two minutes off the beaten track to explore a cave and kill an elite mob for a slightly better drop. I'm talking about somewhere that is in no information you can get in-game aside from visiting, which takes half an hour to reach even if you know where it is, and which can be considered a full dungeon. Deep caves, complex ruins, mountain peaks - the world should be a vast and dangerous place full of wonder.
I feel like FFXI has this in abundance. There are so many places that are utterly unique and just explorable. There are crazy things out there that you can't find out about from within the game with exploring. You can only find out more by discussing it with the community.