Hi Mindi!
Though question about the source of the bias. Personally I think that most prominent sites are "aware of their customers", i.e. they believe that their readers are 13 years old and need to have nice graphics and a short attention span.
I do believe that money to an extend influences the news and previews of reviewers. News and screenshots equals more customers... Further, if you have a prominent name you get attention even if it isn't really deserved.
I think that there are many people how will check out the game website directly if they found a promising game in the preview news. Therefore I think it is a good idea to build a website for the game you are trying to sell (like the m...rix...g-company does ;
).