If you don't have much room then why not just borrow them from the library. Its a free service and you take them back and swop them for another when you've read it.
Various reasons.
1 - I prefer to own my books, it means I can't forget to return them
2 - The library doesn't have many new books that I'm after, nor do they have a lot of technical manuals I need
3 - The library isn't necessarily open when I feel like picking up or returning a book
4 - If I own a book, I can re-read it when I feel like it or put it to one side for a while
Books will still be around long after the Kindle has become obsolete.
And why's that a problem? I doubt it's true as such, since new model eReaders will be improving as time goes by and it's a technology which isn't going to vanish, but I don't see a problem with treating a Kindle as a disposable resource.
It's the second eReader I've owned, the first being a Sony which was misplaced. I used it for a long time, and got through a lot of books. Because ebooks tend to be cheaper than paperbacks the amount of money I saved in prices, bookcases (I'd've needed at least another two for the number of books stored on it), and rent (my house is already stuffed full of books, I'd've needed somewhere bigger) more than makes up for the cost of the reader.
I'm curious why you seem to be so against them though. I was originally, until I actually tried one.