About for the Witcher 2, yes, Celan summed up my opinion. I am -not- offended by nudity, in the "prude" way or anything. I quoted Witcher 2 because it was used a marketing tool. It's extremely difficult to show how a game is featuring mature themes as in political turmoil, philosophical questions like ambiguity and what is good / what is not, psychological scars ( not in the j-rpg term of the ways where 15yo are hiding a troubled past .. Geez! Mommy and Daddy were stealing their pocket money? ), treason, love, friendship, responsabilities.
No, it's impossible to show that in a trailer. So how does one will sell his game? [censored], blood, one liners.
As I said, I put Witcher 2 on my shelves for now, but I like the depiction of the victors rauaging the city they'd just capture, I like the rendering of the King's assassination. The Scoia-tael is a nice concept, mixing racism with rebellion, while not being nice guys/heroes. The Witcher's universe is kind of a grey area. Even Geralt is no angel.
Still the only thing I, as a non-initate, know about the game, is that we got to see titiZ. What does that say? No, it doesn't say that I don't know the universe ( well it does but that's not the point

). It says that what I am shown of this universe is nudity, profanity, gore. It says what the problem is in the video game industry : they are well aware that this will appeal to the largest audience and sell the game.
Tried Heavy Rain? This is also a very mature game. Loss, fatherhood, guilt, responsabilities, and how far you are ready to go to save your child. Mixed up with a children serial killer case. Heavy Rain had great mature theme, with no need for nudity. Well, they did it anyway, two shower scenes ( one male one female ), one love scene. As a result, they felt a biiiit out of place but were true to the Hollywood inspiration. At least, it's not "Triss is completely nvde but Geralt is still wearing his pants".
The Black Company I also mentionned earlier conveys a lot of mature themes, and, just like the Witcher, it's an heroic-fantasy / medfan world. There are hardly explicit six stories - at worst the narrator fantasizes about the Lady. Same mature themes as for the Witcher ( according to you all, since I can't say for myself! ) : war, political intrigues, betrayal, who is bad/who isn't. The heroes are mercenaries, ready to take anybody's money, without giving it a second thought. [censored], stealing, killing, nothing is forbidden. it's never depicted, though, making the thing even more disturbing. To them, to the narrator, it's perfectly OK.
Bottom line : I didn't like the Witcher 1, I don't know yet about the 2. But using the lamest and cheapest "mature" themes to do the selling was bad. It just showed how nudity ( as well as violence and profanity, mind you ) is not, ironically, a mature concept for video games yet.
Bonus : when was the last time you saw a heroin or female character who was not depicted as a sixy chick rather than... Say... A normal or even badass woman? I was ready to go with Samus Aran and then remembered she is getting increasingly longer and longer screentime out of her armor, and increasingly bigger b00biZ. A few women in MGS, maybe. Heavenly Sword's Nariko? Almost, not quite. Lara Croft...? Well we all know one of her, err, biggest features. Fem Shep in Mass Effect? yeah. Oh wait, she has lace bras in the 3rd. Under the armor. Elena Fisher in the Uncharted games? Getting somewhere. Alix in Half Life 2? Yeah.
So as it stands for Dishonored, nudity wasn't needed. Actually I thought that seeing those girls in dirty rags and messed up make-up was far more telling of what they had to live each day. The most "erotic" thing we will see in the game will be those two girls dancing slowly, like they don't have the strength to take it anymore. I found those two girls heartbreaking, honestly.