It wasn't always bad. It was mediocre with some good parts once in while. And with a kitten ending.
Making NS in this kitten ending wouldn't have saved the ending, but at least one thing would've went right.
Instead of getting a 100% screwed up ending, it would've been a 99% screwed up ending.
I really could argue that making NS canon would have made the entire ending better. Hear me out, because NS needed nothing more than a "confirmed couple" shown, then you didn't need to spend two movies, several hundred interviews, side-manga, nor novels to try and explain why SS and NH became canon. That means that instead that time could have been used to explain how Naruto truly made world peace, solved issues, and the like.
This is all assuming of course that Kishimoto actually is a competent writer. He doesn;t even need to be a good writer to make the ending better. Just being a mediocre writer would have given a better ending.