I don't have that much experience with earlier editions, havign only started playing D&D in 1999, near the fag end of 2e, but from what I've read D&D was never really close to medieval. The Renaissance is a much better period to compare it to, and even then, much of it seemed shoehorned into a pseudo-Renaissance feel to me.
One of the reasons I find the (admittedly rare) complaints we see on ENWorld about anachronism in D&D quite amusing is that I've always figured an authentically medieval or Renaissance feel in D&D would be really strange. The medieval and Renaissance periods (focusing on Europe, esp. western Europe, here) were the results of a large number of historical events/movements, some of which were really arbitrary or coincidental. Having a fantasy world with magic, monsters and all the other appurtenances thereof which accurately replicated such periods without the existence of said events/movements always seemed quite hokey to me. An accurately medieval/Renaissance feel in a fantasy world which has never seen the rise of Christianity, the Black Death, the Crusades, the Protestant Reformation, etc. makes no sense to me.
That's also why the "modern in medieval drag" criticism strikes me as a little silly. D&D as "authentic" medieval or Renaissance would be nonsensical, without such vast change to the ruleset (the drastic reduction or outright removal of magic, for one) that it would be unrecognizable as D&D. A D&D setting, IMNSHO, should have a mixture of medieval, Renaissance, & modern elements, as well as more than a few that have had no existence in our world. One obvious reason is to create familiarity and allow players to identify with characters and the setting. The other reason is simply because the existence of the mechanical elements of D&D need to be recognized in the setting. That's one of the reasons why Eberron works well for me as a campaign setting. As Storm Raven said above, it makes explicit what has been implicit all along, tries to envision a world and societ(y/ies) which actually respond to the mechanics of the people, creatures and forces living within it, and also retains enough elements that we are familiar with to allow players to enter and interact with it. That's the kind of mixture of gamist and simulationist elements I was trying to put in my games from almost the moment I started playing D&D, and I'm glad it's being done now.