So I think there's to main sides to this. Add more and/or discuss?
1. Movies can be games and still be art. I think there are some other films that take this angle, though maybe not to the same extent that Inception did. Even a novel like The Great Gatsby has this layer to it- it's fun just to unravel the layers of plot without even really considering its moral implications. (Personally I think Inception is like a lower quality Great Gatsby; its morals/philosophies are redundant and are only present to support the puzzle. I think the "reality has many layers" and the rest of that meaning of life stuff is kinda old. But hey it makes for good puzzles.)
2. Also related to The Great Gatsby. I think its interesting to think about the money involved in making this film. Is the whole film in limbo? Its not very poetic for a movie about dreams, at least from a storytelling perspective. (just an adventure movie) From a visual, technological perspective, though, it's stunning. What would Inception be without the money supporting it? Do you think that it is ethical to spend so much money on our dreams?
Obviously I'm biased but I want to hear the counterarguments since I honestly haven't thought all of this out yet and some of it just came out as I was writing...
.