...I thought the District 9 thing was explained in the movies. Or maybe I have magical mind-reading powers that I didn't know about o_o.

But man, I totally hear you. Time/money constraints suck for movies that really need that background info. And for those of us who aren't into comics, that means we never get those holes filled in until we stumble across it on a wiki years later.
Or we just write EVEN MOAR fanfic to fill the gaps for ourselves. :p