I think the concept of Super Saiyan God was just a natural move.
They probably thought about the scenario like:
- "Okay, we know even Super Saiyan 3 is completely powerless against Birus the first time, what could make a difference for the final fight? How can you become a threat to a god?"
- "Well, you'd have to be a god warrior yourself to fight a god warrior!"
- "That's it! Why don't we make Goku a god warrior now! That could be the ultimate step as a warrior and climax to the story! Something higher than Super Saiyan 3! A new supreme transformation, to become a god!! Rightfully called 'Super Saiyan GOD'!!"
- "Yeah! I like the idea! Having to come up with a design and characteristics for Goku transformed into a god is quite exciting for me!"
jjgp1112 wrote:
God, I hate this bastard. Yeah, destroying planets for his own personal amusement is one thing, but he's a fucking poor sport over video games. Fuck that guy

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Well, to be fair, it is possible Kaio bragged a little too much about his victory! We know how Kaios love winning (or having their champions win)!

So it's easy to imagine Kaio got a little too carried away when winning that game and pissed off the God of Destruction a little!
But at least, he learned a lesson he's trying to teach Goku now: don't play with Birus, he might get pissed and the consequences could be disastrous!
