Because I wanted someone to commiserate with me while I wait for book 5! And behold! My scheme was even more successful than I had planned, for Mom is now hooked on the series too! We can all wait together!
Of course, I did feel somewhat bad about this so I've promised that when A Dance With Dragons comes out, I'll buy them a hardcover copy. So we can all read it together. Whenever that may be.
(I promise, this will be the last time I grumble about the wait for A Dance With Dragons. I'm a writer, I know how these things go.)