Naruto and Sasuke have a brotherly bond, they both embrace it in their own way when around each other. Naruto finally getting to fight alongside Sasuke for the first time in years, obviously brings that bond to the surface in a major way. When is the last time you saw Sasuke smile as well, ntm Naruto's father is fighting alongside him. His first interaction ever with his father in the outside world, his first positive interaction with his brother/best friend in years, also his little Hokage competition talk with Sasuke. He has found some normalcy/comfort in this twisted war which is just a testament to Naruto's personality. Also Naruto has never felt the need to put on airs, especially around people he cares about.
To be honest I don't remember Naruto doing his goof walk, eating Ramen, or his Harem Jutsu and accusing people of being perverts. It isn't as if he is letting his guard down consistently, the situation with Pain was different. True it was an enemy overwhelming powerful, just like it is now. However, he was one on one with Pain, with a level of knowledge on his abilities, and had some strategies seemingly planned out. There is a lot more going on with the Obito/Madara situation, and tbh I don't even see him acting like a complete moron. If he was able to go against Juubito, like he was against Pain the situation might be a little different. The Juubito is growing more powerful, Naruto and co have been fighting for days(sans the new arrivals), it only logically that dangerous situations will become more prevalent.