The cameras are good enough. So pick one and move on.
Agreed. The camera is the lowest sticking-point when it comes to a good looking film. There are a variety of fine choices available at an insane number of price points.
Here's the harsh, sad truth -- most people who want to make films, will never make anything worth watching. They either don't know what that stuff means, or they have nothing useful or valid to say (that anyone wants to hear). Or they have the drive, but they don't have the talent. Or they simply can't be bothered to take the years it takes to learn how to be a good storyteller. There are many reasons why the failure rate is so high. So you're asking a nebulous question. And I think you're unnecessarily complicating the matter by getting way too pedantic about it. Just like with the camera discussion.
But even in your example, you talk about failure due to having nothing useful or valid to say or not a good storyteller, ect. It's already been established that "failure" on a content level is purely subjective. I don't think Dan Brown tells a very good story, yet his books sold tremendously well. Someone might think Joss Whedon has nothing useful or valid to say, and yet he just helmed one of the most successful comic book movies ever. The Room and Birdemic are arguably terrible amateur films that, when taken critically, having nothing useful or valid to say, and are not presented by a good storyteller, and yet they have their audience. It's all completely contradictory and thus useless as a guide. All I can tell you is that I don't want any film I make that looks like The Room or Birdemic, regardless of whether or not I'd still get an audience. I am not personally fulfilled by that.
So here's what counts and here's what doesn't: make an experience that entertains people, and you've succeeded. Obsess about cameras or in any way think that shooting on one camera will give you some advantage over shooting on some other equally-capable camera, and you will have failed before you even started.
I do not disagree with this at all. But you can't just ignore the camera. In film, picking stocks was just as crucial to the pre-production process as anything else. In digital, we don't have stocks, we have cameras, and a careful selection of your tools to achieve the effect of your film is necessary.
And while this conversation goes around and around in circles, it just points out once again that if people quit wasting all their time pixel-peeping, they'd actually have more time and brainpower to devote to those thornier subjects such as "what would make for an interesting story and an entertaining experience?" Of course, maybe that's why people obsess about the pixels, so they don't HAVE to face those questions and those subjects...
But they can only answer that question for themselves. If this thread has shown anything, it's that taste varies wildly and "good" content is entirely subjective.