[Eleutheria]

Felt it was an asspull as (1) from Naruto's point of view senjutsu has always been nature's power that was drawn into a guy, but somehow Juugo just totes it around as part of himself; (2) it's not something that can be passed on to others (although I guess Orochi's sufficiently advanced technology makes it possible); and possibly (3) because it was just so easy and rushed. He literally got the power-up in two or so pages.

I don't read speculation so I cannot say if it's been bandied about or predicted.