I always maintain that they should stick to the pathfinder system but allow you to get flying at your own pace. If I've completed every quest in every zone, done all the extra things to do there and spent hours upon hours running around on foot and seen everything there is to see, what reason have I got to not fly?
I'll admit I love flying and I totally understand why they don't want people flying over all the content skipping everything they've worked so hard creating just to get to the quest objective without experiencing the world. But once you've done that over and over, adding a "Part 2" activator achievement you can't get until some arbitrary patch later on is just stupid tbh. Once I've seen everything, I should be able to choose how I want to experience it.