The more I think it, about the more I realize... Cabin in the Woods was ahead of it's time, and that's why it had an even mixture of likes and dislikes. Modern society just wasn't ready for this kind of tongue-in-cheek satire. Mainly because most of us are too stupid to understand it, and that's part of the problem. Someone needed to point out what was wrong with modern day horror films, and Joss Whedon did just that.
The problem was, it was too intelligent of a film for the feeble minds of today's common moviegoer to handle. They either didn't get it, or the claim to have gotten it but hated it for other reasons, most of them not even valid reasons. Everyone people disliked about it could be easily chalked up to something done bad on purpose to make fun of how utterly stupid horror films have gotten.
The movie is riddled with cliches to make fun of cliches, it's ironic and self aware. It's a bold, daring move more directors need to take. Joss Whedon even said it was his love-filled hate letter to modern horror. He feels the old ones are best and VERY FEW newer ones are actually any good. And I agree. I haven't seen a GOOD horror film in a LOOOOOOOONG time. I've seen ok ones, I've seen decent ones, but nothing worth rating higher than a 7 or 8. No 9s or 10s in years.
Next time someone decides to do an artistic masterpiece of a commentary on screen, HOPEFULLY we will have cognitively advanced enough by then to fully appreciate it. As of right now, society just lacks the intellectual perception needed to appreciate such genius.