This OP-ED PIECE has some of the best arguments against this that I have read. As a writer, I was particularly taken with the following:

Authors' original texts should be sacrosanct intellectual property, whether a book is a classic or not. Tampering with a writer's words underscores both editors' extraordinary hubris and a cavalier attitude embraced by more and more people in this day of mash-ups, sampling and digital books — the attitude that all texts are fungible, that readers are entitled to alter as they please, that the very idea of authorship is old-fashioned.