I had pretty much the same attitude as you. Why buy an ebook reader, when print books are just fine?
Then I found myself alone in a hotel room, at 2 AM. I was making the 2 day drive back home from visiting family for Thanksgiving. The bed was awful and I couldn't sleep. Usually I can read a bit and get to sleep that way... but all the print books I'd brought on the trip with me, I'd already read, and left them with the family for them to read.
I booted up the netbook I had with me, looking to go online to read something... and the hotel's wifi was so slow it was maddening. Even when I got to my favorite blogs, even, no one had updated anything because it was Thanksgiving and they had better things to do than provide entertainment to a desperate guy in a hotel far away from home and any open bookstore.
It occurred to me that if I had a Kindle, I could order a book right damn then, and start reading.
So I ordered it. Didn't get it 'til I got home, of course. And now I'm loading it with a ton of books so I doubt I'll ever be without something new to read (unless the battery fails). But as long as it's working, I can get a book RIGHT NOW. Any time. Almost anywhere.
That's the advantage to me -- not so much the ebook in and of itself (although they've been fine so far), but getting it immediately.