We already had a thread about this
The problem is not so much the mainstream authors, for whom such information is available on sites like Fantastic Fiction, but the indie books on Smashwords where there might not be any other place to learn about the books. Authors who are not known and are trying to build a fanbase need to make it as easy as possible for new readers. If I can't tell at a glance what book is first, I skip over the whole series. I just don't have time to go hunting around for it.