You basically just described everything wrong with the leveling process, and how utterly and completely disjointed it is.
Garrosh is the entire reason we go to WoD in the first place. He caused the Iron Horde. His actions lead directly to AU Gul'dan bringing the Legion back to Azeroth. Which in turn leads to Sargeras plunging his sword into the planet.....which leads to why our characters have the HoA.
You can't just cut one piece of that story out and have it still make any kind of sense. As I described in the rest of post you quoted, dropping a player in at any point after cata, but without context, is just as bad of a situation as the current leveling "story". And the speed of leveling is almost mutually exclusive to telling that story in a way that makes sense; the faster you level, the more disjointed it gets.
I'll be REALLY interested to see how Blizzard resolves it with a level crunch.
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Yes, they have. Take a look at this ridiuclous situation from Reddit, where they describe just how badly broken the situation is:
https://www.reddit.com/r/wow/comment...rofessor_whom/
But as long as they're going to do things like mess around with level scaling and level crunch, they might as well go all the way and completely overhaul and redesign the leveling experience. If all they're going to do is just leave things as it is and smash 120 levels down to 60, they might as well not bother.