To add to your comments on travel, reading position, lighting, some books are just too large or heavy to lug around or even hold for long periods. There are a number of door-stopper books that I otherwise just wouldn't have read because of this.
If the medium makes the difference between me reading a text rather than not reading that text, I tend to think that makes it functionally "better".
If the medium makes the difference between me reading a text rather than not reading that text, I tend to think that makes it functionally "better".