I also realized after looking over my (physical) bookshelves that I don't actually care about most of the books on there. This is after multiple rounds of clearing out the shelves and making trips to the secondhand bookstore, free library, etc., so it's not a matter of cruft. If I'm honest with myself, most books are "read once and discard," though there is a small collection that it feels distasteful not to keep copies of. Certain classics, or books with particular personal significance, for instance.
The cost of ebooks is an issue, as is the DRM. I haven't experimented with digital lending from libraries so I don't know if that's a solution to the cost problem, but it could be. DRM is... well, a perennial problem for digital media. And it does feel like something is missing in a world without secondhand stores and free libraries.
(Edit: It is in fact a frontlight, not a backlight. Duh.)