But that part hasn't really changed. There are still a few quests that give good items and others that do not. Blizzard changed it a little with Cataclysm but the gear through leveling is still all over the place. Which is one of the reasons why heirlooms as scaling gear were implemented. You can't have your cake and eat it too. Because that cool sword will be out dated as you quickly gain 10 levels from the XP boost.
There never was a full set of gearing per zone in the game. This really is a case of rose tinted glasses while wanting to force everyone to play that way. Level scaling doesn't change anything at all. Because rewards are only the level at which you earn them. It means that even in one zone you could theoretically have a 10 level gap between the items. You will have huge gaps in the power of gear. Which means that either gear will have to be meaningless so as not to impact the difficulty or their will be drastic difficulty changes depending one when you do certain quests for the reward you need.
The current alt I am leveling is still wearing a item level 34 bracer, 48 gloves, 44 belt, and 46 boots at level 52. I haven't got an upgrade through quest or a world drop. Obviously the item level 40 items aren't to big of a deal. But the bracer is a huge deal. That isn't a "super awesome" experience that is being missed. This is why the scaling item level of Heirlooms are just as important as the XP boost.
The faster you level the worse the gearing process becomes.