Why Kabuto wanted young uchiha? Can it be something connected to the knowledge Orochimaru was hiding? Senju/Uchiha Rinnegan creation experiments...?
I thought that was explained in the manga - he wanted to be in an Uchiha body. Yeah, probably so he'd implant Hash-man's cells into it, then.
He obviously wanted to have his own Rin'negan, and it also helps that Sasuke is pretty powerful on his own, and already accostumed with Sage Energy/Cursed Seal.
I agree with our moderator Uchiha-blood! kabuto obviously wanted a rinnegan,but that's not all: he wanted the true essence of ninjutsu. do you remember that jiraiya,in a flashabck of volume 48 (nagato's flashback) mentioned a certain ism,that is the "shinsu" or something like this (I cant' remember exactly). probably that shinsu is the true essence of the ninjutsu.