Moon and the science fiction genre

I just finished watching the brilliant film Moon, the debut from director Duncan Jones. In case you're unfamiliar with the sci-fi film starring Sam Rockwell and too lazy to click the link, I'll inform you of the basic plot. Sam Rockwell plays Sam Bell, a lone astronaut, who is living on the dark side of the moon in the not-to-distant future. His only companion is a computer named Gerty, voiced by Kevin Spacey. He is in charge of manning the station and harvesting Helium 3, an alternate fuel source used to create nuclear fusion. At the beginning of the film, he is involved in an accident and wakes up in sick-bay. Going out to check on the harvester, he finds another astronaut unconscious in the moon rover, who happens to look exactly like himself. Hijinks ensue.
This is the second time I've watched it, the first being when it was in theaters, and I am still just as impressed. It reminds me of the classic science fiction stories of the fifties, and, to be honest, of the early science fiction novels. Now, granted, I am more of a fan of fantasy and faerie romance than science fiction, so if some sci-fi buff out there disagrees with me, feel free to voice your opinion; but I maintain that the early science fiction was simplistic. Novels such as H.G. Wells' The Time Machine, War of the Worlds, In the Days of the Comet, or The First Men on the Moon were quite simple in their plots.  As well, all of the novels listed above were social commentary. Also, C.S. Lewis' science fiction--his Space Trilogy--are, again, simple stories. Peralandra has a tiny cast of characters and very little action. While That Hideous Strength sports a much larger cast, it as well is a simple story, which one could narrow down to a romance about a dying marriage being saved. Granted, I've not read the science fiction of Edgar Allen Poe yet (mostly because I tried and got bored) and I have only tapped the surface of Verne, but if what I've read about them is any indication, Verne is little more than an adventure novelist and Poe's work is not much different from his horror and detective fiction.
My point being, one of the reasons I consider Moon the best sci-fi film of the passed ten years is that it is adhering to the example of it's predecessors. It succeeds for me the same reason the original The Day the Earth Stood Still succeeded while the remake was terrible. The director and writer had a simple message to convey and they told it simply. We didn't need to see a stadium dissolve for the original to move us. I first watched the original in 2008, shortly after I heard about the remake, and while the remake's special effects were substantially better, the original was far more superior in context.
I know that most people out there are singing the praises of Avatar, and it is the second highest-grossing movie every made; but I've also been reading everywhere that without the special effects it is nothing worth seeing. The official budget of the film is $237 million. You'd think with a budget like that they could've afforded well-written dialogue and an interesting, unpredictable story; but instead we just get flashy special effects. That's all good and well, but I think once those special effect wear off, Avatar will be just another sci-fi flick, while Moon--or even Wall-e(in my opinion, the second best science fiction film of the last ten years)--will still be considered a masterpiece and a classic.