Because that's how the show works.. every action carried a reaction and consequences. It would have tanked the entire show when suddenly in the finale everything was fixed, the cancer wouldn't kill him for some miraculous reason and he would get to keep the money to start over somewhere else.
He just had the fortune to be able to keep it together for one last time to tie up loose ends and go out with a "small" victory (as Vince Gilligan put it).
Walt managed to say goodbye to Holly; managed to provide for Junior; saved Skyler from Lydia and the Nazis; finally reconnected to Skyler by suddenly growing the balls to finally be honest; finally overcame his obsession with money by killing Jack Hitler; even reconciled with his son, albeit the surrogate, Jesse! About the only thing he didn't triumph at was beating cancer.
Maybe in his head Gilligan thinks Granite State showed Walt finally beaten, and Felina only shows Walt winning small. But, thematically, Walt wins big in Felina. I think that the only thing that kept the episode from grinding it in the viewers' face that they were Team Walt all along was that, when Walt suddenly became the hero willing to accept martyrdom, that we had Jesse the anti-villain rejecting cold-blooded murder, of anyone, not even Walter White.
At the beginning of the series, Walter White, afraid of dying and contemptuous of everything he has in his life, breaks bad. Everything after was about trying to live in memory as Heisenberg and using his money to control his family after his death, ways of denying his mortality. His rediscovery of courage and acceptance in the last few episodes is not really very believable. It's gratification for Walt identification.