The program with having people go though the leveling experience is that it is old content, with old design, and new player mechanics that causes it not to vibe that well. Even if someone hasn't played WoW, they don't want to do stuff that is 7 years old.
Cataclysm attempted to correct that by redoing the original part of the game, but ultimately it ended up being a so-so investment, as only new people and those who wanted to level alts got to do that content, and blazed though it quickly.
What is the easy way to get new people to new content, while letting older people feel like what they have isn't being thrown away? Free level boost to the new content. 1 per account. However, this causes an issue where under the current system someone can buy another copy of the game with the expansion, and transfer their characters to the new account. So they simply cut this "workaround" and provide a rather expensive way to do it that is a bit cheaper.
Take off your ruby colored glasses and face the fact that as much fun you had getting a group together that managed to do blood furnance early in BC expansion, you forget the hour you spent getting a group together that had to include a warlock to keep all those NPCs feared that would otherwise overwhelm you. You want hardcore -- easy, do mythic raids, the day the are available. See if you can full clear the raid in under a month and join the world top players in fame.
Oh, and there is no flying in the new expansion areas.