On Topic: Bring back the World Map. I call B.S. on these people saying "We don't have the tech." Okay, fine. Disregard the fact the the PS3 is a powerhouse. You can at least FAKE it like you did in X. Shops and towns--with actual people to talk to--is a step in the right direction as well. XIII felt very empty and lonely. When I finally got back to Cocoon at the end, I was like, "Oh yeah, there are other people in the world. I forgot." Finally, make the characters special and unique. Give them their own back stories that, unless you explore the game, you'll never learn about them. XIII was better than XII in this regard, but not by much. Remember in VII where, unless you explored, you'd have never found Yuffie or Vincent, never have gotten Yuffie's quest, or Vincent's complete back story. In VIII, you could go on a quest to find about about Squall's parents helping those Moomba creatures, or Zell's little fling with the girl with the ponytail. These little touches made the characters seem like actual people, not a ragtag group of heroes.
And for the love of all that is holy, never, EVER make it so every character can use every weapon. Stupid XII gambit system...