Because sometimes less is more.
Yes, we would have missed out on ome good visuals, but we would also have a stronger connection to the world we are made to inhabit. Shadowlands isnt like Zandalar or Kul Tiras, there isnt any firm preexisting lore for players to really get invested in to begin with, it has to start from the ground up, which isnt exactly the strong suit of WoW.