Doom and Gloom

I watched the movie "Doom" last night. I did it because, even though I knew it wasn't going to be a good movie, I did play the game for awhile. So, it's a loyalty thing I guess. My take on it: Why is a restricted movie displaying nudity and extreme violence scripted as if it were written for children? Also, can anyone else picture "The Rock" playing Ray in "Rainman"?