I think Kishimoto must have been aware of the fan revolt concerning this issue which is why he made it so that Obito took the Hachibi and Ichibi; therefore, maintaining the fact, which he stated again recently, that when a bijou is extracted from the host, the host dies. Kishi has made a few mistakes like this during the process of writing the manga, but I still believe they are minor and do not take away from a great story. In fact, once the war boiled down to the main antagonists/protagonists (especially with the resurrected Hokages), I think he's been on a spectacular run of story-telling. I've been consistently anxious in waiting for the next issue for the last 6 or 7 months now, I've really been enjoying the story. (although I still haven't been able to figure out why he's turned Minato into such a fail character?! After Naruto and right next to Itachi, Minato is my fav char.!!)