It would seem that Blizzard has focused on getting their players to end-game a bit faster, within the latest patch for World of Warcraft the following has been implemented:

Leveling Improvements
Many leveling improvements have been made for the old world.

• The amount of experience needed to gain a level has been decreased between levels 20 and 60. In addition, the amount of experience granted by quests has been increased between levels 30 and 60.
• Level 1-60 dungeon quests have had their experience and faction rewards increased.
• Many elite creatures and quests in the level 1-60 experience have been changed to accommodate solo play.

Looks like this means Blizzard is going to focus on End-Game content and let the pre-Burning Crusade content sit on the shelf. Personally, when I was playing WoW I liked the lower level 'old world' content better than what Burning Crusade added to the game. A level 70 version of Wailing Caverns (or Deadmines, for you Alliance folks) would be bad ass.