I have mixed opinions on this.....

I think that not every player of FF is hardcore. Some people like to play it like a walk down the park. In that case, I think that having a fairly easy final boss works.

For more hardcore FF gamers (like me), I'd love my final boss to kick some serious ass. Penance for a final boss on FFX would be awesome, since it would encourage me to spend time level building and such.

I think what would be better was if FF games in the future had a difficulty setting. Most games have one, why not FF? If you've gone through the game quickly on Easy, you could then have the option to pump up the difficulty level for more die-hard FF gamers.