Quote Originally Posted by JAS4Yeshua View Post
and when it was over, the game is over, and you can't go back to those optional bosses to defeat them.
What are you talking about? You can always go back to an earlier save. Heck, there aren't even any save points in the final area in FFXII so you can't save after the point of no return.

Anyway, the point of the optional bosses is so that those who want more of a challenge and more play time from their game can take them on. If you got all the fun you want out of just beating it, then just beat it and ignore the extra content. Those who just want to beat the game don't want to jump through all the hoops and level up to 99 just to do it, whereas those who want more of a challenge want to fight bosses that can be tough even at rediculously high levels.