There's a small but vocal portion of adventure game fans who I swear actually hate adventure games and everything about them. As Steve said, it's across all mediums now, not just games. I'm a massive Doctor Who fan, as if anyone here didn't know that already, and I get onto their biggest fan forum and every single week regardless of what happened in that episode people are crying the end of the universe because it's ruined everything about Doctor Who for them. I swear their reality and the real universe are two different things.
As a game author, I appreciate constructive complaints, those things we can find and fix, but a lot of the time it's just generic "this game sux" sort of comments. Or, the graphics are crap. Or, $20? What a fucking rip-off for a game, it should be free or $5. Those sort of comments have no basis in reality.