Of course it has to do with SEO. The reason to write those fake reviews is not (only) to get people reading those before the product is out, but mostly to have better google rankings (page age seems to have some weight).
This might be true, but once the Wii U starts to receive legitimate reviews from credible sources, these 'faux' reviews will be crushed by the authority of Gamespot, CNET, etc. providing real reviews that are accumulating great number links. Right now, these fake reviews are killing the SERPs because there is nothing else to return for reviews of the Wii.