This expansion, in particular, focuses on the Alliance/Horde war. Fighting NPCs in a Warfront or bosses in a raid instance (or any instance, for that matter), doesn’t really constitute a war.
That’s part of the issue some have with Warfronts to begin with. They would be fantastic if they were PvP and there was a chance to lose. They are tolerable, at best, because of the gear reward (toys/pets/mounts in the “off week”) because they are fights against NPCs and there is no chance of losing the “war”. So much potential lost to poor implementation.
Also, that’s not what folks are talking about.
They are talking about random encounters with “enemies” in the actual world where the war would normally take place. Those types of encounters can’t happen if everyone is in the air miles above the “action” (causing there to be no action). For some, that diminishes game play.
Personally, I don’t care about PvP, instanced or world. I don’t PvP much and when I do it’s a random BG or the old “PvP WQ” areas in Legion for Honor to get the pet/mount/title rewards. But for a lot of players PvP is their main game-play. For them being grounded can be fairly important.
Blizz could “fix” the issue simply by having flight unavailable while WM is turned on, but they won’t. They could have done the same thing when PvP servers were separated and they didn’t.
But claiming that the "plight* (for lack of a better word popping in my head) of PvP players based on PvE largely not being effected by it is a bit disingenuous and short sided.
I, for the most part, agree with most of what you’re saying…from a PvE players perspective. But I can still see the other side. I think that is the basis for most forum “wars” (also for lack of a better word)… One side simply can’t, or won’t, see any validity in the other side.