If your book is fiction, the print version can do without a table of contents. Since it’s more difficult to find your way around an ebook, however, a table of contents is not only helpful but required by some ebook distributors.
Generating it through Microsoft Word, however, is not going to work properly. Per the Smashwords Style Guide, you should bookmark each chapter heading, which is then connected via hyperlink to the table of contents. This works nicely for the Kindle version as well.