No, flying helped make them completable as both expansions required flying just to get to specific areas.
Flying allows the developers to make much larger scale, and add more levels of height to their environment.
But at the same time, without flying they can make areas feel larger then they are, and make the environment more mysterious and dangerous to navigate, which I’m pretty sure was where they wanted to go.
Now, I’m not gonna say they were successful with this, because they weren’t, personally I would have taken it into a different direction, and added vastly more to the “journey” they hoped it would feel like we are taking. But they fell short, and it’s a shame tbh.