Some people here seem to ignore that Blizzard obviously did not want them to explore and complete ALL Azeroth quests to become a lv60 character. The way it is created right now is that there is 4-5-6 different "paths" depending on your starting position and your faction.
That said, you all gotta consider a lot of things.
1) Old WoW was a condensed lv60 experience with 5-6-7 Zones completely focusing on lv55-60 contents, repeatable grinds, factions with reputation gains, and group grinding mobs with level 61-62-63 (Darkwhisper gorge, anyone?). This is simply not sustainable, not efficient. There is no point having a content which no one could play. Because the players depart Azeroth the second they hit lv58.
So consider this: Blizzard have basically freed up 40% of their previously "high-end 60 solo content" place, and made them into lv40-30-50 places where there are a lot more quests, flight paths and quest hubs now. You cant force a player to spend one month in Azeroth before he can depart to doing the "real deal". Considering that Burning Crusade is already a weekend-like content, and WOTLK should not last more than a week either, it is perfectly fine and acceptable. If you want hard levelling, unclick quest shows on map, read quest lines, and go into the wilderness without BOA stuff and doing dungeons via Dungeon Finder.
2) Old WoW had a LOT of unneccessary painful time sink. Lv40 for first mount? Lv60 for fast mount? People were in outland without epic mount just 2 years ago, but now a lv40 char can fasten his/her question by 2-300% just by not running there on foot. Obviously, that is one time save. Other is having a lot more flight pats, and more condensed quest hubs-> one place, 3-4 quests, repeat -> next hub style. But, let us not forget the highest amount of time-sink saved: THE DUNGEONS. Now, in the old world, going to Scarlet Monastery (lv34+ place, so you went there ON FOOT, traveled half a continent!) took at least an hour, if you were not so fortunate that you got a summon. Gathering quests to there as an alliance member required various Kalimdor->Azeroth->Kalimdor journeys, again, via with a boat and your feet. And then the instance with the harder playstyle of the old times. Now? You get teleported in, you got a LOT of free, hugely rewarding quest XP without any prequests, and you have an easier time in there.
I just cant imagine a scenario where I would demand that quests would be harder to obtain for old school dungeons. I cant demand slower travels, less teleports, no Dungeon Finders, or nerfs to all classes so early instances will be hard again. I cant demand dumb "run through forests for hours between questgivers miles away from each other for 2-300 xp" scenarios to make a comeback.
The new WoW actually has an intelligent design, where, if you make 2-3 new characters, you can level in totally different places, where you have not been before. You can make the choice between a bit more instnace farming for a fancy blue, or a bit less, with more outdoor questing. And there is PVP. It is insane how much this have improved on the early content, and how can anyone miss the old system.