You make a great point that lot’s of si-fi are mostly present-day allegories, like the HG Wells stories were. I think some contemporary si-fi shoots itself in the foot in using cinema vérité style… It’s just not the language of allegory. It could work, but the concept has to rise to the level of realism that the film-making technique is suggesting. District 9 does a good job of this for the first section and sort of devolves once it forgets it’s original documentary conceit. But by that point, you’re already on-board, so it works.
Maybe I’m forgetting other examples where it works well? Never saw Cloverfield so I can’t comment on that.
As a side note, George Lukas actually intended Star Wars to feel ‘real’ and to have a documentary feel– hard to imagine that!
