A great game that needs very little adjustments. I too played the heck out of it (went as far as to erase the sphere grid's 1, 2, and 3's, and replace them all with 4's). It was a nice mix of challenge and limiting (for a short time) on your ability to grind to a certain degree.
I hope they don't add online components because Square's history with online servers, and their security, aren't exactly stellar. An option for Japanese or English voice-over would be nice, although I don't have the problem with the English voice-over that everybody else does. It would be nice also if reaching certain goals in the game, unlocked art galleries, and special features. Other than that - if it ain't broke, don't fix it.