What, exactly, does one lose if they choose not to fly and instead ride along the ground? Outside of war mode, at least.
A little bit of time, sure. But that's the whole point of taking the ground route, you want to appreciate the sights along the way. So that isn't really a "non-optimal" way of playing. It's actually more optimal because you're getting the enjoyment you crave.
You don't harvest nodes as quickly. But, given that this is a terribly poor way of making an income in the game and it's vastly more efficient to just swipe a card for a token to sell on the AH this doesn't really seem very "non-optimal", either.
I guess you might miss some rare spawns that die to the people flying to them before you can get there. But is this really so important that it's worth wrecking the desires of the majority of players?
I can't think of anything else that might be "non-optimal". What are people doing in the game world that requires 100% efficiency over desired gameplay? Most of the people that hate flying seem to be instance-runners, anyway, who barely interact with the game world at all, if they can help it.
Blizzard's attitude towards flying is just a symptom of the rot that has caused me to drop WoW. It's this insistence on optimizing every aspect of the game for a small few that play in their preferred manner, which sucks all the actual joy out of the game for everyone else who just wants to have a good time. I don't think most people are having simple fun in WoW anymore, they're almost all just playing for the next dopamine hit. And it's not their fault, Blizzard has designed it this way at the behest of the tiny minority that demands hyper-efficiency at all times.