My biggest selling point for this would be, that the volume is probably the same throughout the whole text. I am listening to audiobooks to fall asleep, and many voice actors go from very quiet to loud in conversations. It may be good narration, but it's sometimes to quiet to understand, so I need to increase the volume only to be woken up by some loud lines later.

So I imagine generated audiobooks to be good in that regard. Another option would be to have a "normalize volume" setting at audible, or other services.