I would be happy with this resolution. I would be much more inclined to buy audio books if I can get them in a non obscure format.
ALL drm is useless, not just that protecting audiobooks.
Useless? Netflix is based on DRM, maybe you find it immoral, but it certainly isn't useless.
They don't have everything. They have a small, patchy, selection and a bunch of torrents are completely dead even for popular publishers.
ffmpeg -activation_bytes <your activation bytes here> -i file.aax -c:a copy file.m4a
I have a few more commands to extract and re-add the artwork.