Well then you are grossly mistaken.
No I didn't. People can form opinions on something like this without seeing it. It's not hard to read the books or to find detailed descriptions from those who have read/seen it.
Sure, some of the people are prudes. But, most of the backlash is from people who recognize that Christian Grey is a cold, jealous, controlling, mentally and emotionally abusive son of a bitch. And that people acting like anything he does (not talking about the sexual stuff in the slightest) is okay is completely fucked up. Totally not the message we need to send to females. That guys like that are hot and any of that is excusable. Lots of this coming from people who have no problems watching porn, so there's nothing prudish about it.