I read a lot of objections to the Kindle stating that you don't own the books. Personally I read a book once and I'm done with it (unless its a programming/reference book). I assume most people are the same way. So why hoard books if you're not going to read them?
The other thing is that "buying" a book for the Kindle is more akin to "renting" the book. You don't own it, Amazon does. You don't own a DVD you're renting from Blockbuster, or Netflix, but I don't hear people complaining about wasting that money.
I also think that if I'm going to read a book more than once, I'm going to buy a hardback version of it and keep it on my bookshelf. If not, then I'll buy/check-out a paperback book and donate/return it when I'm done reading it.
I think there are really two distinct kinds of books, and critics often confuse the two.
(I don't own a Kindle, but have given some thought to it and read up on people's objections)