It's your choise. Probably you have done that because you have already play Legion, got fly and unlock Allied Races or simply you dont care about that things.
But a new player? And if its ok for you, why must be ok for everyone?
You can denied that is a Game Design issue, but a Game Developers cant. This must be solved... and probably Level Squish and Class design will take into account that problem, expecially if Level squish will allow you to choose whether to start from any expansion and make all the necessary levels there.
Also, you are thinking how the game is by now... but probably the next expansion will brings changes.