Lol. Can't take it away, Hagoromo? You know, I still don't get how Naruto works in the movie? No BM? No whatever final powerup? I just don't get it.
Got to love this movie, it's actually saying "kitten you, Naruto's story" because Toneri didn't started to work on plan after he saw Kaguya or any kind of it. He was there whole time. It's basicaly nullifying whole story of Naruto, let alone his feelings for Sakura or bonds with Sasuke.
Hagoromo. Worst hype for a character ever. For years, we've been wondering what he looked liked and what kind of individual he was. He turns out to be nothing more than a floating pacifistic geezer and on top of that a horrible father who had to prefer one of his sons of the other one 
Many people belived that he wore forehead protectore with horns, just like Jiraiya with kanji "sage" or smth like that. That he was the only one who created all things with his yin/yang jutsu that was based on izanagi.
Hagoromo truly is an idiot. Thing is it could've been done in such a way that it make some sense. For example:
Sasuke: I want to kill Naruto.
Hagoromo: Normally I would not even consider helping you since you told me what you want to do but with the circumstances being what they are, I have no choice but to help you as well in order to save the world. Only by combining the power that I gave you with the power I gave Naruto will you guys be able to defeat Madara. I hope I won't regret this decision.
Plot device, not even a character, he could give both to Naruto it's not like they awoke it by themselfs, he gave it to them, he was ok watching for the third time how both his sons would kill each other.
I know right, there shouldn't have been a massive power up in all honest, I mean Sasuke getting the Rinnegan I can get, but Naruto getting a power up like without training as you mentioned does take away from the series theme. In all honest because he had Biju Mode I thought that because it was Yin Kurama his cloak would've been dark compared to the other half, I still would've been fine with that. And tell me abotu it when it comes the concept of Teamwork...
It really surprises me when people kept telling me that you should drop Naruto for good reason back then, and I kept telling myself I'm gonna see this thing to the end and now I really regret it...
Although I guess getting this ending did help me respect Fairy Tail alot more then how I use to, also giving me a chance to try out Boku no Hero, Tokyo Ghoul, Sukedachi 9 and get back into One Piece.
Getting Rinnegan wasn't even suppose to happend. It was established that there was 3 ocular powers, not 2 with eternal evolution of one.