Still, maintaining perfection is difficult and draining oft enough, yes?
As you probably are well aware, for as simplistic as it pretends to be on the top, and in the early stages, it evolves at an alarmingly large rate. And the evolution path never really stopped right up 'till the end. The subtle depth behind so much of the game is still what impresses me to this day, and despite that I don't play anymore, I was still learning new little bits up until the day I quit.
Party support, aggro management, typical roles, chains & bursts, all that good jazz while keeping it fast and fun rolling up the EXP chains was quite tricky, and it's something that had to come with a lot of pratice and time.
I'd say it is a difficult game, even moreso when comparing within genre. Warcraft is much more manageable and accessible, which are good traits, but it takes them to a severe fault. The grouping in WoW along with the PvE game on the whole really lacks vibrance and cohesion, IMHO.
Edit: Mad, if you don't think FFXI is a polished, immersive game within MMO's, then I'd be somewhat terrified to know what you think is. The game still has by far the best controls, physics, animation and by FAR the best lore, plotline (only in the genre, really) and sophisticated world design in the genre.
The game did control much better on a PS2 pad though, yes. Perfectly so, and no, I'd kill SE if they ever added RP servers.