I'm finally back to writing again.... chanting *not going to make kishi's mistakes, not going to make kishi's mistakes!*
Yes, I've wondered to if the dramatic story shift isn't because of Kishi having to work on it exclusively and continuously from about age 20/21 to 40/41. There's a lot of differences in those ages!! Single to dating, married to having children!! And I definitely think that softening, becoming more aware of Japan's social issues right now leaked into the story and characters.
It's a shame he couldn't have stopped at some point, taken a break, let the story breath, then gone back and read Naruto from the beginning again. Maybe he could have remembered what the story was about before committing to an ending that was so out-of-whack with the main hero.
He knew the parings were and why nH and ss didn't mesh with his story. That's part of the reason why the last chapter felt so miserable. Also you can blame the pairings on his staff. Which led to both it and the last abandoning all the morals and character arcs so hinata could get what she wanted. So that all depends on if he caved to them or not.
Now before the ending that maybe different. Since like i said the goal of naruto before pein arc could be summed up as "Reform the ninja system" after the pein arc it was all about "ending the cycle of hatred" -after minato gave his speech about that and early jiraiya mention the prophecy it what naruto's arc became about other then sasuke- and I'm honestly not sure if it was kishi or the editors who did that. Either because kishi didn't know the goal of Naruto becoming hokage and the message it was suppose to send (stand up to corruption and reform you system of government if it is corrupt) because yahagi was incharge of that. Or if every new editor saw those bits and thought that was the tangible (or at least the check mark goal to say he did accomplish the thing he set out to do) end goal of naruto other then saving sasuke.