Why Obito felt the need to pull out the chakra? Plothole?

[Kαmi]

Because he figured Naruto was the one who would be able to have the best chance at beating Madara than him, Kakashi and the others. Bringing Naruto back along with the other chakras so that he could get all 9 pieces was just a smart move on Obito's part in order for Madara to be beaten.

 

[Ultimateone]

it's simple, and by no means a plothole, i not sure you know what a plothole is. the reason is simple, just giving the other half of kurama to naruto would be pointless other than saving his life. in the end he'll face an even more powerful madara and get the kyuubi taken out again, thus killing him for good. so obito knowing naruto had the power of the other bijuu decided that he should take the risk and get the rest of he chakra naruto needed. it wasn't just so naruto could pull ot the bijuu from madara but so naruto could gain a new power. everything doesn't need to be explained, especially when they are very obvious. so again not a plothole.