Do You Really Need SEO?

Only if you want to get targetted traffic directly from the search engines to your web site. Otherwise you most likely don't require a search engine optimization on your web site. 

Search engine optimization is geared twords sites that need to increase their exposure and aquire new visitors from the Internet who aren't aware that their web presence exists, not to mention being the best source of advertising, as once you're at the top of the search engines for your  specific keywords, you don't have to pay to be there.