Plot, my friend, plot. For now, Kishi wants to show Madara as a beast. Soon, Naruto and Sausage will power up again and defeat him.
But why will Naruto use only sage mode to face Madara when there are KCM, BM, and BSM all highly above SM? You have to be at your best to face Madara like how Sasuke is using EMS..is Naruto out of kyuubi juice?
Common that guy is fighting for last 24 hours, Going up against
6 Jins, 6 Bijuus, Saving the SA's ass twice, Fighting Obito and Madara, Juubi then Jubito and now madara.
What more do you expect from a kurama jin with 50% power