Website Usability is important in website design. If your visitor experiences cognitive overload (has to think too much about navigation or what to do next) then your Information Arhictecture may need re-evaluating.

Search Engine Optimisation is not just about getting a search to clickthrough to your landing page. Once they reach your page you have a maximum of 10 seconds to engage them or they will leave. If they are not ready to buy from you right now then you must give them a reason to come back. A timely offer maybe? Or a newsletter signup.