Okay, but then you’ll also likely never be able to fly in extra areas added after the expansion launch. To use MoP as an example, you couldn’t fly in Isle of Thunder or Timeless Isle, both of which were areas added after the expansion’s launch.
Personally I think Legion was a sweet spot; we knew it was coming from the beginning, and by the time all the Azeroth-related content was released we could unlock flying without further delay. Lore-wise, flying would have made no sense on Argus anyway considering the constant barrage the Lightforged and Draenei ships were under when we first arrived.
Granted, the mob density in Kul Tiras and Zandalar can get annoying, especially when you have gathering professions, but as long as Blizzard follows the Legion pattern and allows flying to be unlocked for most if not all Azeroth-related BFA content at once, I’m willing to put up with the frustration of having to stop and fight off a hundred mobs every once in a while when I just want that Anchor Weed spawn.