You bring up some good thoughts, and it takes all kinds.
File size is a real consideration. The Federalist Papers is just under 700mb as audio.
https://librivox.org/the-federalist-papers-by-alexander-hamilton-john-jay-and-james-madison-2
Here are 2 files of the entire Bible. As just plain ascii text, it is almost 5MB. Naturally it is a bit smaller as an epub, since those files are compressed.
-rw-rw-r-- 1 amp amp 1.4M Jun 2 2015 /var/www/html/books/The_Bible-KJV.epub -rw-r--r-- 1 amp amp 4.8M Jul 7 2006 /var/www/html/books/The_Bible-KJV.txt
I use the Bible as a way of describing how big a MB is. Most folk have a good feel for how big the Bible is. Once they know that it is approximately 5 MB, the can get a better idea of what a megabyte is.