I use to overlevel when I was younger with the idea that my characters would be super strong and that it'd be cool to kill enemies in one hit. I still do when I play through a new FF for the first time. When i've done all that I find that it IS a lot more fun to play out the battles as they would in the story - not killing the enemy in one hit.

Of course, on the first play through file I'll beat the game then spend time going to level 99 before I smash the secret bosses etc. Next play through has gotta be more challenging. At lower levels it tests your skills as a Final Fantasy player. Winning battles by recieving 10 damage and giving out 1,000 isn't skill.