I have to disagree with this very strongly.Brother MacLaren said:The biggest change was the unifying mechanic of d20 plus modifiers, higher is better. That made a lot of sense and was generally well-accepted. Additive multiclassing was more intuitive and more elegant than the 2E version. Feats didn't seem a big deal at first, just allowing for a bit of customization (I certainly didn't perceive how much of an impact Power Attack would make). 3E really didn't change any game design principles the way 4E looks to. Demihuman level limits almost never came into play in 2E, so removing them wasn't a big deal; opening up all classes to all races was interesting, but IME you still mostly saw dwarves as fighters, halfling as rogues, and elves as whatever they wanted to be -- just as in 2E.
3E radically changed the design of D&D. Whereas in AD&D character build was essentially uninteresting - for Fighters it consisted entirely of weapon selection (or NWPs if that optional rule was in use) - in 3E it is a huge part of the game (feats, skills, PrC etc - do you think that core AD&D could possibly give rise to a character optimisation board?).
Likewise, in AD&D action resolution itself was not the focus of gameplay - the combat rules were simple, and the non-combat rules handwaving at best - but rather the consequences of action resolution, often as adjudicated by the GM. In 3E action resolution is a huge part of play.
These two factors combine to lead to the complaint that 3E has neutered the GM.
The nature of adventure design has changed also between 1st ed and 3E, to reflect the changing role of the GM and the changing approach to character build and action resolution.
Compared to these radical changes, a few cosmetic changes to tropes - Dwarf paladins, 20th level Half-Orc thieves - were trivial aspects of the AD&D/3E transition.