Plus if I have a moment to read and I want a new book, I don't need to wait 3-5 days for shipping, I can download it instantly. If I'm ever out of the country (as I am now for half a year) I can still get any book delivered to me instantly. For me that's just a convenience, however it's critical for areas that normally have to wait 15-20 days for shipping from a place like Amazon.
EDIT: As a quick note to your edit, you're really ignoring some of the best parts of ebooks while pointing out their worst. I don't own a Kindle however read ebooks through Amazon on three different devices.
But buying something is different - buying is, by nature, a matter of value. The fact of the matter is, buying a second hand book gives you more value/dollar than buying an ebook at 3 times the cost. An ebook you read once but cannot resell is eight dollars literally lost overnight. You no longer have the eight dollars and you don't have anything worth eight dollars. When you buy the book second hand, you get the same (or better) value of reading the book, but you also retain a residue value that lives forever.
When I travel, carrying a lightweight kindle or iPad is simple and doesn't take up tons of space like the 3 giant paperback books I would read without an e-reader. Plus, assuming I bring an iPad, it does tons of other stuff as well.
On top of that, as other people have mentioned, all the syncing that is done between reading devices is fantastic.
Also, I can read in the dark on my iPad, and I can read with white words on a black background, which is much easier on my eyes.
I definitely agree about the advantage of e-books when I travel, which is why I sometimes buy light entertainment that I don't care about owning in e-book form.
Reading in the dark is one of the worst things about iPads, however. Light that is reflected from a page is much easier on the eyes than light shone directly into your eyes, even if it's white on black. I wouldn't presume to argue with your personal preference, but I find the eyestrain of a glowing screen in the dark to be a considerable drawback.
With almost any popular, still-under-copyright book, this is what the pricing looks like on Amazon:
http://www.amazon.com/Harry-Potter-Sorcerers-Stone-Book/dp/0...
Paperback: 8.79 dollars. Kindle: 7.99 dollars. Used: 1 cent. Used via Amazon Prime: 3.98
To save NINETY CENTS you get an arguably inferior copy that you cannot resell, pass on, share, touch, or truly experience. No, thank you. And don't forget that your Kindle cost a hundred dollars - you'll need to buy a hundred and eleven such books before you're actually "saving" money.