I remember when that happened with the ebooks. One day you could buy ebooks in multiple formats, including PDF, or ebook + paper book for about 25% more, usually. Then we woke up one morning and the only digital format was Kindle and you could no longer buy direct from O'Reilly in any format.

I still think their books are among the best edited and informative on the market but their business practices are getting less and less appetizing.