I work with ebooks a lot in my job and I'm often asked if books are dead, if they will die, or why they are not dead. Ebook growth has leveled off significantly as devices to read them became ubiquitous and cheap, so its sits more or less flat at about 35% of the market (give or take).
I often turn the question on the asker and ask them to analyze a book like its a piece of technology. It's lightweight, extremely durable (survives a five foot drop to concrete no problem) and inexpensive to replace. It's UI is really unmatched since we've been taught it since childhood, but on an objective scale it's easy to jump to exactly where you want (though difficult to search). It's resolution is fantastic and I've never tested it, but I've heard the battery life is great. It's a wonderful single use device, and single use devices certainly still have a place (after all, you can make toast under your broiler, but plenty of people still have toasters).
End of tangent.
There's absolutely no restrictions on when I can use it (flying, jury duty), coupled with all the other reasons you give... really is the perfect solution for many use cases.
What I personally don't have is the desire to have lots of books around. I keep a handful handy, but try to get rid of ones that I won't re-read, lend, gift, or didn't have HUGE meaning to me.
Books are great, but are really quite feature-poor. You frequently need to install add-ons to get even the most basic capability - like bookmarking, or increasing font size. You definitely don't get search, a built-in dictionary, or the ability to trivially share excerpts.
All in all, I would definitely recommend this product to users with good eyesight and memory, but other potential users may want to go ahead and upgrade to ebooks.
Finally, though search is lacking, users have developed some clever ways to overcome that issue over time including indexing and tables of contents.