If you don't know what is and isn't working, you can't improve, right? your website is no different. You must know what your website visitors like and don't like to keep them coming back for more!
Make it easy on the search engines to know what your website is all about! Having a sitemap on your website makes it easier for them to index your website and who doesn't want to make things easy for search engines? I know I do!
There's nothing worse than getting excited about clicking on a link only to find it goes to a 404 error. Not cool! Get those broken links fixed and keep your website visitors happy!