While I understand that certain measures need to be respected, personally I believe that if I own something in one format, I am morally (not legally in the UK, I believe) entitled to convert it to another format for my own use. So, if I buy a DVD, I will not think twice about ripping it, or downloading a copy "illegally". Books are no different in pure terms, although I have never sat there and scanned an entire book (as it is not worth the time and effort, to me). I have, however, downloaded electronic copies of books I already own from less reputable sites. Morally, I see nothing wrong with this: I bought it, I just want it in a different format.
I, personally, don't believe they should allow licensing terms which prohibit this, and I think it should be legal. If I bought a VHS copy of a film many years ago, why should I be forced to pay again for exactly the same content as an electronic copy? Same with eBooks: I have a large number of books, but now want to store them on my tablet or ereader. Why should I have to pay again (normally a higher price, even though there is no physical media)?
At the very least, I believe that you should be able to send a book back to the publisher and be granted an electronic copy (if not free of charge, at least for a very low fee). At least then they know you don't have a second copy, you have just format shifted the first.
The law needs to catch up with technology.