While 95% of my library is in English, there are sometimes that I really miss some literature in German. Also, sometimes the version in the original language is so superior and you miss nice details or ambience on the translation (like the Count of Montecristo in French). And now I have to learn Dutch and want some books to start.
In summary... not finding a book in it's original language bugs me, but... I'm willing to make sacrifices for the greater good (which is the worldwide sharing of books).