I have to disagree there. I don't play fantasy games to see an exact copy of real life, there are lots of games set in the real world to satisfy that desire, and while I can't name any good open world RPGs set in the real world, there are a fair amount of open world sandbox games with a realistic world, look at Red Dead Redemption, for a while. When it comes to fantasy, I want to see worlds that are strange and unique, this doesn't have to mean giant mushrooms, but they should stand out from other fantasy worlds in some way, and for the sake of that, sacrificing some realism for artistic license is a good thing.
I see what you mean, but when I play a game, I want to do things I wouldn't do or wouldn't be able to do in real life. For this to be fun and interesting, I need the game world to be realistic. It doesn't have to be an exact copy of real life. In the case of TES games, I'm fine with things like magic and monsters, but for the game to be believable, it should look realistic.
Shame Red Dead Redemption isn't available on PC. So far I haven't found any other open world games that I really enjoy besides Oblivion, FO3 and New Vegas.