Board Thread:Theories and Speculation/@comment-26119997-20150219181955/@comment-4912646-20150220000723

Hagoromo strongly implied that something happened to Kaguya when she ate the fruit. The databook talking about how the Shinju grew by feeding on the blood of dead humans also paints in a negative light, making it hard to believe the tree is truly an innocent, ambivalent being. Personally, I assume the tree somehow tempted Kaguya into merging with it, as there is really no other logical explanation for why she would choose to do so. Jin no Sho says she become Ten-Tails as part of a plan to retrieve her sons' chakra, but even Kaguya can't be stupid enough to come up with a "plan" that nonsensical.

I mean, willingly taking on a distinctly weaker, much larger (and thus an easier target) form that she apparently can't control or easily revert back from? It just doesn't make any sense if she wasn't somehow being manipulated/affected by the fruit. There's also the contradictory fact that she wants to personally own all chakra, yet creates plant soldiers that have chakra of their own.