I think it is really stupid. It is one of if not the dumbest thing to ever happen in this manga. First off it is pointless. The fourth hokage is plenty strong without the kurama chakra, he did not need an immediate power up. And if kishi wanted to show just how strong he is and why he was eared he should be using jutsu he had while he was alive. Even if he did not have to worry about kurama's mind I doubt he should just be able to turn it on like a light switch. It destroys the entire concept of training and learning new jutsu. Jutsu re not this easy to learn so it is a little hard to believe using kurama's chakra is this easy. I thought it was really cool at first but as I thought about it I just found it stupid