I was mistakenly comparing the ground area to the size of the bird instead of to the size of Link, so yea it is the same scale or close enough, but it's still irrelevant. You don't use the bird to traverse Skyloft. You use it to fly between islands, and it doesn't do this job much faster than Epona takes you across Hyrule Field.
Again, I don't have a problem with it. There's not much to do in the sky anyway, so I spend hardly any time flying, and flying is different enough that I enjoy the leisurely pace.
I'll be more careful what I post from now on.