Many SEOs obsess over search engine algorithmic details. They spend hours looking at the minutest of details hoping to achieve the perfectly “optimized” web page. In the process they often forget that the web page can’t just be optimized for search engines, but must also be optimized for human visitors.
Optimizing for spiders and visitors are both important for a web site’s overall success. But I don’t think they are necessarily equally important. In order for the search engines to be able to index and rank a site, a “search engine friendly” website architecture must be implemented. And while having a search engine friendly site is good, it must not be accomplished at the expense of the visitor. At best, it must complement the user friendliness of the website. At worst, it must be invisible.