If you take a non-SEOed site that has the best flash intro and the best graphics on the web and put it up against a well SEOed site, the SEOed site will beat the other one to smithereens hands down in sales. Why? Because sales are a numbers game. More consumers = more sales. You may win a beauty contest with the other sites, but if no consumers can find you or you are buried at the bottom of a list what does it really matter. Joe Blow with his dinky little well SEOed site will be at the top of the list and get first clicks from the consumers.
The good news for the rest of the unSEOed sites out there is that alot of random clicking may someday lead those other consumers to your site...maybe.