I agree though, with most part of what you said. The movie was actually great, and Sasuke's scene compared to Naruto's base Taijutsu fights and his small fight with Toneri were on par, if not equal with badassory of that scene. It was the timing of the scene itself that made it great, as Sasuke came at the last minute to save Konoha. Leaving with only a single word, and disappearing quickly. It was meant to glorify his fans that came to see their favorite character, but it does not mean that it overshadowed the rest of the movie. Despite Sasuke being one of my favorite characters the scene was easily forgettable. Why? Because the movie was a retcon created by SP in the first place, most of the canonical abilities did not even make sense. To the removal of Kurama, changes of Rasengan colors, and the Byakugan nerf. After the Sasuke scene, the next scene that got everyone talking in how badass they became(in my theater at least), was when Naruto shattered the Moon floor destroying Toneri with a punch.
It still all goes to opinion though. People have enjoyed the movie for what it is, and it is making billions in the home country, and still pulling in revenue outside. I do not think it was ever meant to be serious in a Manga sense, it is basically RtN with a canon title on it.