One of the strengths of genre film making is that it provides ample opportunity for intelligent writers and directors to secret social, political and cultural commentary beneath the more visceral, lizard brain pleasures of horror, sex and violence. The appeal is easy to see: you can make an insightful, even subversive point without the audience feeling like they are being beaten over the head with an ideology, while still making a film which is actually fun to watch. It's a tricky bit of misdirection to master, but it's largely why the likes of Invasion of the Body Snatchers, Society and Shock Corridor remain so fascinating decades after they were initially released.