The only thing that proves is that he turned a very shitty story into a slightly less shitty story. You guys dont understand the deeper meaning behind being a writer.
If his story got worse the more he focused on the Uchiha and sasuke(notice how part 1 is much better than part 2?) then he needs to change the way he writes. Plain and simple. Would you rather be a god of an epic universe or a really shitty one?
Writer's prerogative I suppose. I get what you are saying. Honestly I didn't really have an issue with Part I Sasuke and even liked him slightly better than Naruto then. So in that respect I felt Sasuke was a great choice to add in as an antagonist to the series. I think the real issue for me started when Sasuke actually got his revenge and learned the truth about Itachi and his clan.
His decisions from that point on left me feeling like Kishi didn't really know where to take his character. For awhile many Sasuke fans couldn't even justify him fighting Naruto in the end. For all tense and purposes he was a changed man after talking with Hashirama and learning his clan's history so his antagonistic attitude toward Naruto just didn't seem all that necessary.
But hey that's just my opinion on the subject.