PedroSteckecilo is right, D&D has never been a simulationist type game its always been on the gamest side. The world of D&D is pretty clean compared to what a fantasy world would look like. You don't get a gouge in your arm that gets infected and goes septic causing you to lose the arm which may in itself kill you. You tend to lack the factors that make medieval fantasy medieval which tends to make the whole setting fall down under scruitiny.
People tend to be tolerant of random groups of strangers from different races walking into their town instead of instantly suspicious of such a group and likely racist towards those not sharing a species. People who live in medieval type towns would much more likely have medieval type attitudes.
I've recently seen Aces and Eights as a friend has got it and that game looks to simulate. Combat goes down to fractions of seconds to allow people to do quick draw shoot outs, locations include groin and neck to name a few. D&D does a hit and a wound, no other effects, you are either fine, incapacitaded or dead. Going from incapacitated back to fine has nothing in the way of perminant effect, actually same goes from going from dead to fine.
I play WFRP 2nd Ed and that has an altogether more honest Fantasy setting (I would consider 3rd ed but the game just has too many holes at the moment), racism is rampant, class is everything, disease is prominent. In WFRP you are as likely to die from getting stabbed in a drunken bar brawl as you are to die fighting a monster. Wizards are treated with suspicion, anyone that raises people from the dead is hunted down, elves are treated with conempt and fighting the monsters will probably lead you to become corrupt and insane.
Even that isn't really a simulation of a fantasy setting, it doesn't attempt to treat weapons as accutate representations of their capabilities or do use mechanics that would support simlulationist play.
D&D is fun if you like the gamist type of rules set it gives you but it most certainly is not a simulation unless the DM makes a large number of changes to the game. For those who want to know about the difference between gameist, simulationist and narrativist games they should look at
http://en.wikipedia.org/wiki/GNS_Theory.
Kaihlik