I think the challenge was one of the most appealing things of XI. At least it was for me. It kept the casual players away and gave you something to work toward that felt fulfilling at the end. Hitting those milestones is what kept me coming back for more.

On the other hand, MMOs like World of Warcraft, Warhammer Online, and now Rift, are mind-numbingly easy and it doesn't feel like something special when you hit level cap or defeat an endgame boss. Heck, I went back to Warhammer for a 2-week welcome back trial and we killed the enemy leader twice in the same day and I got two of the best items in the game for basically just being there.

A challenging but rewarding game is what I'm ultimately looking for in XIV, and I hope they manage to create or enhance that same sense of accomplishment that XI captured. I don't necessarily want another XI, just another challenging MMO.