I suspect those that didn't like Gravity are frustrated that it didn't include the usual set of story elements that generally make up an action movie, but what they are missing is that the stripped back story is a major part of it's brilliance. Cuarón was trying to visually realize the most profound horror: the moment an astronaut realizes they have become lost to space, detached from the only thing which keeps them alive and linked to the world.
That's it - the other stuff is just fluff. Other movies can be other things and do other things, but Gravity as a piece of art chose to do one thing, and it done it better than any movie before it.