Content is King but Optimized Content is God. Why Because search engines give your site more prominence the more you put into your site.
Before the internet became hip and the MAN started trying to weild it to commercialize it (OK just had to put that in there), the soul of the internet had already been established.
The internet was founded on providing free access to a free exchange of information that would be as informative as talking to an expert on each topic, not slanted or biased in order to sell you something.
The Keepers of that promise are the search engines like MSN, Google and YAHOO. The fact that they capatilize on it well just put that aside for now. Search Engines have found that making their searches more intelligent has clients using them more. Think about it, if you ask it San Diego Real Estate and you get result pages for Viagra, Canadian Meds and Online Gambling you will stop using their searcher.