The problem is that kishimoto no matter what he planned for that final battle; he had only to chapter 699 to do it, because it was already decided to end the manga at 700 and the last to be out a month after the manga ended. Once that idea was decided on; Kishimoto had a limited number of chapter to finish up kaguya, resolve the four undead kage, as well as set up, then have Sasuke and Naruto big fight, and then have enough room for the ending. By the time he got to the fight he had what 5 chapter left, thereabout? Then kishimoto had to try doing as much as he wanted to do in those chapters before he had to quickly wrap it up, and resolve the story as well as set up the sequel Boruto.
In terms of fight creativity, the series had been degrading for the longest time in that department and the use of Naruto's back-to-back-to-back power ups shows. Still, with a few more chapters, I suspect we might've gotten at least a little bit of the "I knew you knew I knew you knew I knew you would do that" approach that made fights in part 1 so interesting.