Sometimes I think it's like a review team; game A goes to Mike, he does what he thinks; game B goes to Serra, she goes with how she's feeling that day, and so on.

Rated T for Tears.

Naw. They get together and discuss each game, then the winner of the mandatory Mario Kart competition decides which rating gets applied. Of course, since only one person is allowed to represent each proposed rating, some employees will lobby for substantially lower/higher ratings just to get a chance to play. And upon winning, the employee will make a more logical ratings determinaton, albiet not remotely based on the results of the earlier discussion.

I want it to be R18 :P

There's a boss in dark souls 2 described as being topless with hair covering her nipples lol. 

There's a boss made of corpses, bosses mostly nude, torture devices, mutilated bodies etc. That's M. I don't know, the game also just generally feels more mature.