[ZGoten]

I wonder why Tobi is fighting Naruto in the first place, if an incomplete ten tails is all he needs to achieve his goal. He could have cut tail hours ago, since he already had the tentacle and the chakra from Ginkaku and Kinkaku. Or he could have just started summoning the beast where he is right now at the time when nobody was around.

But again, this can be explained by Cael's theory that Tobi is Obito's father. He has personal issues with both Kakashi and Naruto. He hates the former, because he couldn't protect his son, and the latter, to seek revenge for the death of Obito. I really like this theory.