I enjoyed, but didn't love this movie

Rating: 6/10 (17 March 2012)

I wanted to love this movie, I really did. I enjoy the sci-fi genre so much, that I even bought Sucker Punch and Battlefield Earth, and haven't gotten tired of watching either one of those movies yet. It's pretty hard to find a sci-fi movie I don't love.
This movie had everything going for it; intriguing concept, incredible cast, and the action-adventure scenes certainly weren't lacking, in any way whatsoever.
What was missing from this movie was the entire back story, and at least for me, that's the most important part. I have no problem enjoying B, or even C rate sci-fis, with cardboard cutouts space ships, just as long as it has a decent back story.
The entire point of sci-fi is to explore the possibilities, to answer the question "What if....?" Well, this movie explored possibilities, but to what? That question is critical, it's the entire basis for the story. It simply doesn't make any sense to create an answer, for a "what if?" question that the movie never even formulated.
What I mean by this is how did the conditions created in this world come about? Obviously, medical science found a way to prevent disease, and stop the aging process, but fear of overpopulation alone is not enough of a reason for those "time" devices. There are other ways to prevent overpopulation, including simply sterilizing the population at birth, which certainly would be far more humane. A civilization with the technology to halt the aging process surely has the technology make "test tube" babies when replacements are needed, so why not? This alternative solution is so horrifying, who could possibly have come up with it, and why would anyone ever agree to it?
Exactly how did those time clocks get on their arms? Was it genetically engineered into human beings? Or is it implanted in the hospital at birth, and if so, no one's figured out that they could save their children from suffering this fate by giving birth at home? If not, why?
Seeing how "stealing" time was just fine, why wouldn't most, if not all, big strong men with 30 seconds left on their clocks, just turn around and find the closest, smaller weaker person and take some of their time by force? After all, if your only other choice is to die, it's self-defense. Who wouldn't defend themselves against certain death?
Developing and incorporating a back story to explain the circumstances under which the conditions in this world were created, would have made the movie more interesting and enjoyable. For example, "WHAT IF... there had been an impending disaster of such magnitude, that it threatened the very existence of the entire human race? One so dire, the only possibility of survival, was by having 95% of the adult population work 10 hour days, 7 days a week, keeping them young and strong to ensure they could maintain 100% production levels that were absolutely necessary to survive, etc...
Instead, there's no back story, nothing to explain how or why those in power are anything other than evil despicable, single dimensional, selfish monsters, who see nothing wrong with not only letting others die, but deliberating creating circumstances to ensure they do. All just they can live forever, in the lap of luxury. They have no qualms admitting to it either.
Even the evilest of villains can usually come up with better rationalizations to justify their actions than that.