That's like asking>Why must I:
Level through Cataclysm
Then go back in time to BC or WOTLK
Then go forward in time to cataclysm again or further to Pandaria
Then go forward but also back in time at the same time to WoD
Then go forward in time to Legion just to hit 110.
THEN I level through BfA, current timeline, to unlock Zandalari!>But then I must:
Level through cataclysm as a zandalari
Then go back in time AGAIN to BC or WOTLK
Then go forward in time, as a zandalari remember, to cataclysm or even worse - Pandaria - who were enemies of the fucking Alliance/Horde/Pandaren during that expac.
Then go back through legion again
AND THEN FINALLY: GO THROUGH BFA -AGAIN-, doing every single thing in the world beat for beat, just as my original character did.>not to forget that I can do timewalking dungeons, which is admittedly explained as bronze dragon timey-wimey magic, but handing in the quest you have to hand it in at old dalaran, which is hidden in Northrend, which is going back in time.
BLIZZARD FIX THIS SHIT.