It's just dumb. Game balancing aside, Bahamut Prime is huge and (story-wise), you'd be harder pressed to miss him rather than hit him. Especially if you're right next to him poking him with a Spear/Sword/whatever. And considering the accomplishments we've made as Warriors of Light, we should have no issue hitting the rear of something only paying attention to the Main Tank.

On balancing... It just means that for the start of progression, you'll probably want to stack accuracy to ensure that you meet whatever arbitrary number is picked out for the required accuracy for your class. That's it. It's just a useless stat that doesn't really do anything apart from prevent us from getting other secondary stats. If you don't end up with enough accuracy, whoop-de-do pop accuracy food. That's literally it. And then eventually people figure out what the actual cap is so that other people don't have to go through the inane procedure of guessing how much accuracy they'll need.