"Dystopian" films often depict an otherwise appealing future ruined by uncontroversial woes such as totalitarian government and environmental apocalypse.
Imran Siddiquee writes about the topics such movies rarely elaborate upon, such as racism and sexism. The future is colorblind, the enemies are evil in mythic and mundane ways, and the subjugated protagonist is white.
Whenever Hollywood does get an opportunity to talk about race in one of these movies, it minimizes the subject. Characters of color like Beetee, Cinna (Lenny Kravitz), who mentored Katniss, or Christina, Tris's best friend in Divergent (played by Kravitz's daughter Zoe), certainly play major roles in these stories, but their race is never at issue. You might say that this is an example of admirably "colorblind" filmmaking—were it not for the fact that the audience's perspective is always that of a white protagonist.
To an extent, the diversity of characters depends on the source material, but producers typically have some leeway in casting decisions. Suzanne Collins, in her original novel, does not explicitly describe Katniss as Anglo-Saxon (she has "olive skin"), so it's actually the filmmakers who make the decision to default to white. In fact, Collins intentionally leaves many lead characters in the novels racially ambiguous, creating a more integrated and nuanced world.
Dystopia was a Victorian rhetorical subversion of contemporaneous utopian thought. So it's understandable that literary dystopias tend to be conspicuously perfect in many ways: it's part of the formula, the jaws behind its satirical bite. Just as "dystopia" now refers generically to science fiction that depicts an unpleasant future, its inherently and inexplicably utopian qualities have become sleepwalking tropes, threaded unthinkingly into its depiction.