This game can be pretty unbearable without flying depending on the whims of the developers. Nazjatar is a prime example. You can't go anywhere on the ground without being dazed off your mount and forced to fight several enemies that pull several more enemies. And the developers overloaded those enemies with annoying mechanics like rooting you for 8 seconds, or constantly interrupting your casts with a 4 second lockout.
On the other hand, Argus was great. The first trip I made through Krokuun was incredible and memorable. Being able to fly there would have cheapened it. And the devs were considerate to add teleporters around the zones so flying needn't be missed.
I'm fine with Pathfinder and timegating as long as they make the ground gameplay more enjoyable than flying over it.