Adding to the discussion, The Chicago Manual of Style gives the traditional reason for numbering front matter and main text separately in both form and count:
"The front matter of a book, especially in the United States, is paginated with lowercase roman numerals.... for some of these pages (for example, preface, acknowledgments, and dedication) may be expanded or even added at the last moment. If arabic numbering were to begin with the half title, no page could be added to the front matter once the book was in page proofs." Mike Wickham
