Sorry, but I don't see how OoT fully explains his origins, as you claim. The only information about Ganon that we get from Oot is that he's first serving the king of Hyrule and that Zelda has a bad feeling about him. Nothing more. We don't see how Ganon even got into that position and why he...
Well I had an idea similar to #3 some months before E3, I was thinking that the game would revolve around the Master Sword and its coming into existence and I thought that we'd learn the backstory about Ganon(dorf). After seeing the trailer and all the related stuff/information from Nintendo, I...