Since I know what spawned this conversation, I'm going to go in a different direction. I'm also going to spoil both Inception and The Wrestler in this, so everything's going to go behind the spoiler button.
I think you're problem is in your expectations. The story you think you're being told is different from the story that's actually being told. The Wrestler and Inception both have rock-solid conclusive story endings, they're just not the conclusions you're looking for.
The Wrestler isn't about whether or not Mickey Rourke lives or dies. The outcome of that final match is irrelevant. The story is about what choice he's going to make. He loves to wrestle, but it's killing him, so he quits. He's doing well in his new life, but then he's reminded how much he loved his old life.
The story is about making that choice between two worlds. At any point up to where he leaps off the top turn buckle, he could have backed down. He could have changed his mind, stopped the fight, walked away, ended it. It doesn't matter where the story goes from the moment he's in the air because that's the moment his decision is final.
It's a similar thing with Inception, and this is part of why I dislike that Nolan got snarky and included that final shot of the top. The story is about Cobb overcoming Mal and returning home. Whether or not Cobb is dreaming is irrelevant to the story, which is why it's so easy to manipulate everything to fit either version of that debate.
Cobb is away from his family. Cobb needs to get back home. Once he's home, it no longer matters to him whether he's dreaming or not. He's where he wants to be. When he abandons the top, when he goes to his children, that's where the story ends. The quest we've been watching is finished.
That last shot of the top is snarky misdirection; "You want to know whether it's real or not, but I'm not going to tell you. Nyah nyah." That's not the story, though, and so it doesn't matter except for geeks to argue over.