In the wake of Gravity's critical and commercial success, quite a few people are asking how Alfonso Cuarón managed to make such a solid yet unconventional movie. My favorite article is this interview snippet from io9, in which he discusses some of the changes that various studio personnel recommended.
The suggestions, which range from flashbacks to a Mission Control romance, indicate not that Hollywood is full of morons out to ruin good movies, but that they had different stories in mind. Those other stories might also have resulted in enjoyable films had they been written, acted, and directed well. It seems unfair to dismiss them outright except to note that those alternate versions might have felt less original and less contemplative.
I'm glad Cuarón made the film his way.
This divergence highlights just how much an individual artist's touch can change a project. The same premise in two different hands will likely develop into two very different books, movies, TV pilots, or what have you.
Such a world of possibilities can make storytelling intimidating. If there are a thousand possible stories dwelling in one premise, or even in one set of characters, how do you know which one to tell? On the other hand, perhaps this means there's enough room for any of the versions we might dream up.