DD, I think we are talking about the same thing.
Using your example: If it were a real book, I wouldn't have bothered to open it on the bus or train. I can't get comfy with it, and hold it at a good angle. The print may be a bit too small so I have to hold it closer, and my arms are getting tired. I don't like having to wrap the other pages around the back to hold it in one hand. I go to highlight something and it bleeds through the pages and makes the other side hard to read, so I just stop trying in that book. Something in the book makes me think of a passage in another book, I am near a stopping point anyway so i would like to switch gears (say from computer tutorial to fiction to biography).
All of these things with a physical book deter me. They stop me from enjoying the content like I should.
Now (of course I don't have an e-reader yet, so these may be rose colored glasses I am using) all of these things are NOT an issue with an e-reader going through the SAME book.
I am sure if I found the right set of circumstances (book size, nice paper, good print size, nice area to rest arms, etc.) I would enjoy a "real" book as much as the e-reader, but because the e-reader's physical nature is ALWAYS going to be constant (and the print should be relatively constant depending on formatting and such) none of those other issues that I would have with a "real" book are issues with the e-reader.
So, all I am left to do is get lost in the story and then curse that I missed my stop.......again