I'd never given much thought to Hyne when I played the game. I just always looked at Hyne as a legend passed down through the oral tradition. They have two different stories in the game about Hyne, once in Balamb and once on the White SeeD ship if I remember right. I figured it was just a story to flesh out the world more.

That being said, I think it would have made a lot of sense to have the big bad of the game actually be Hyne. Since he was split in half, he could have been trying to create time compression in order to reunite with his other half. I think I've heard theories before that Ultimecia might actually be Hyne or somehow related to Hyne... which would help build motivation for what she was trying to do; however, there is not much in the game that I remember that could hint towards this.