Howso? Exchanging eyes are the natural process for Uchiha, to further develop themselves. Naruto just constantly leeches off of Kurama's chakra/power 24/7; 365.
I know it was foreshadowed, but atleast let Naruto develop himself on a certain level, because Naruto without Kurama is kind of sub-par.
Who says he still can't even with the 9 tails. He can still develop himself, but to get to Madara and Hashirama's level would take years and years of training without the 9 tails. The 9 tails counterbalances the years of experience Madara has.