I buy them in mobi when I can, which is not infrequent for English language books. But French publishers have arrived on the market later, and they made the seemingly logical choice of the epub format. Apart from pdf, epub is almost the only format you can find on French ebook stores. I just hope they don't take too long to figure out how to make decent ones... and I do hope they will drop DRM some day, or at least settle on a less annoying scheme than Adobe's