It's kind of funny when you have films like Mission Impossible: Ghost Protocol or Source Code or X-Men: First Class with 94%, 92%, and 87% rottentomatoes ratings. Yet it's Oscar bait like this and this that always gets mentioned when awards season arrives, while those other films get nary a mention. The Harry Potter films are a perfect example of this. Some of them got really great reviews, but nobody seemed to give a damn outside the box office.
I've long said Peter Jackson's greatest accomplishment was getting me to watch the Oscars [and care] three years in a row.
I agree there are scifi films over the years that should have been nominated... but I wouldn't include any of those. Plus no matter how good the reviews are, I think there's still a difference between a film that's purely entertaining (like a Mission Impossible), and something that's truly a work of art that deserves award consideration (like The Artist or the Descendants).
The Academy Awards have never been a popularity contest, they aren't supposed to reward the best rated film, most succesful just on those terms. It's about how it works as a whole, acting, script etc.. That being said I think there is still a certain stigma attatched to the Sci-Fi/Fantasy genre when it comes to general film/TV awards.
I saw Source Code, didn't bother with those other two. It was a fun flick, but let's face it, gimmicky and shallow, as genre movies so often are, when they don't suck outright. I certainly hope there were ten better movies this year (I never find out till six months to a year later since I rarely see anything that tempts me to spend $10-$12 on it). I only saw 1 1/2 Harry Potter movies before getting bored and giving up on the whole series. They're nicely produced movies I suppose but once again, that's not the sort of thing the Oscars goes for. There's definitely a stigma on the sf/f genre, but by and large, that stigma is earned. I'm less interested in seeing Oscars for genre movies than I am in getting a decent space opera series back on TV.