I would counter by saying that that experience can be found in the current expansion and end-game.
Making progression through old expansions tedious is not really a good way to go about creating the environment you're looking for. Moreover, the game has grown to such a degree that doing so would result in a truly bloated process rather than a fun adventure. That's what we had before now: A process, not an adventure.
This is why I think it's good what they're doing with chromie time. Although the balance isn't quite right to make 1-50 take an entire expansion, I'm not convinced it needs to be. Maybe there should be sn option for that to appease people looking for what you described, but for those interested in leveling fast to reach the current expansion, the way it is now is very good.