Why did Naruto have trouble controlling the Kyuubi at the first place? Because it hated him and wanted to break free. In this last chapter we found out it was protecting Naruto by not absorbing his chakra while he was using its chakra.this is a change of its behavior and if it decides to truly help Naruto in the next chapter it'll leave him in control of its full form. That is how Hachibi and Bee do it, or perhaps both of them are in control though they have an agreement who to act when - e.g. Hachibi doesn't do anything while Bee is fighting Sasuke and throwing that tbb around, however it takes control in order to perform that whirlwind spin jutsu we saw that cleared the forest in the previous chapter.
Anyway, if this isn't an argument enough to make you reconsider a bit then I'm not going to go out of my line
In my opinion though this is how tailed beasts who have made a pact with their host act - since earlier in the manga it was mentioned (back in 3 tails capture arc) that hostless tailed bests are "dumber" than those with a host since the latter ones can use the strategies and experience of their host. The Kyuubi may be arrogant but it is smart - it recognises what it needs to survive this war.
